@article{shutayfi_raj_eapen_shannon_2023, title={Design, Modeling, and Analysis of a Compact-External Electromagnetic Pumping System for Pool-Type Liquid Metal-Cooled Fast Reactors}, volume={193}, ISSN={["1873-2100"]}, DOI={10.1016/j.anucene.2023.109997r}, journal={ANNALS OF NUCLEAR ENERGY}, author={Shutayfi, Mohammed and Raj, Anant and Eapen, Jacob and Shannon, Steven}, year={2023}, month={Dec} }
 @article{shutayfi_raj_eapen_shannon_2023, title={Design, Modeling, and Analysis of a Compact-External Electromagnetic Pumping System for Pool-Type Liquid Metal-Cooled Fast Reactors}, volume={193}, ISSN={["1873-2100"]}, url={https://doi.org/10.1016/j.anucene.2023.109997}, DOI={10.1016/j.anucene.2023.109997}, abstractNote={Current pool-type Liquid Metal-Cooled Fast Reactors (LMCFRs), either under development or operational, immerse main reactor components in the primary coolant, (i.e. sodium), that includes heat exchangers, shielding structures, and pumping systems. Proposed main pumping systems, for some reactors that are under development, use electromagnetic pumps (EMPs) for primary coolant circulation. Annular linear induction pumps (ALIPs) are the preferred type since they are known for their advantages over mechanical centrifugal pumps (MCPs) when used to circulate liquid metals. This is due to ALIPs’ absence of moving parts such as shafts and impellers, seals and bearings, auxiliary lubrication systems, and simplicity of flow and pressure control mechanism. The immersion of reactor components in the primary sodium in the reactor vessel minimizes the likelihood of radioactive coolant leakage and loss of coolant accidents. However, since there is only one access point to reactor components, the immersion of ALIPs prevents additional potential advantages. Online pump inspection and replacement, reduction of negative effects on pump components due to the high temperature and radiation environment, an additional heat removal mechanism for self-cooled ALIPs, and simple decommissioning procedures are some possible advantages. This paper discusses a study conducted to investigate the possibility of using large EMPs, ALIP type, that are located outside the reactor vessel and connected in parallel, instead of in vessel sodium immersed ones for pool-type LMCFRs. The large, outside-vessel EMP idea is tested on a liquid metal-cooled test reactor design using an experimentally validated multiphysics finite element analysis tool. Specifically, the steady state reactor’s primary circuit cooling and pressure requirements are used to design two, in-vessel ALIPs and then two outside-vessel ALIPs. The two pumping systems are compared in terms of their geometries, performance characteristics, and impact on overall reactor design. It is found that the outside-vessel EMP design provides the same performance requirements and offers additional advantages compared to the in-vessel pump with only minimal reactor vessel modification and a slight drop in efficiency.}, journal={ANNALS OF NUCLEAR ENERGY}, author={Shutayfi, Mohammed and Raj, Anant and Eapen, Jacob and Shannon, Steven}, year={2023}, month={Dec} }
 @article{du_kruger_nam_lee_yoo_eapen_kushner_shannon_2022, title={Comparison of glancing-angle scatterings on different materials in a high aspect ratio plasma etching process using molecular dynamics simulation}, volume={40}, ISSN={["1520-8559"]}, url={https://doi.org/10.1116/6.0002008}, DOI={10.1116/6.0002008}, abstractNote={In plasma etching for microelectronics fabrication, one of the objectives is to produce a high aspect ratio (HAR) via and trench structures. A principal contributor to the HAR feature shape is the manner in which energetic ions interact with sidewalls inside the feature. The scattering angle and energy loss of ions reflecting from sidewalls determine the sidewall slope and can lead to defects such as microtrenching and bowing. Understanding how ions interact with sidewalls can improve our control of the critical dimensions of HAR features. Ions accelerated in the plasma sheath arrive in the feature with energies as large as a few keV and initially strike the sidewalls at glancing angles. These scattering events extend to the photolithographic mask. Scattering from the mask at glancing angles can produce ions incident into the underlying feature with a broader angular distribution, leading to less desirable feature properties. In this work, results are discussed from Molecular Dynamics (MD) simulations of glancing-angle scattering of argon ions from three materials common to HAR etch: polystyrene (as a photoresist surrogate), amorphous carbon (a hard mask material), and SiO2 (a common insulating material used in microelectronics devices). Results from simulations reveal a transition from specular scattering to diffuse scattering as the angle of the incident ion decreases (90° being glancing incidence) and incident energy increases. Scattering from polystyrene is more diffuse compared to amorphous carbon and SiO2 for identical incident ion conditions.}, number={5}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Du, Yao and Kruger, Florian and Nam, Sang Ki and Lee, Hoki and Yoo, Suyoung and Eapen, Jacob and Kushner, Mark J. and Shannon, Steven}, year={2022}, month={Sep} }
 @article{moneghan_shkoukani_eapen_bourham_mustafa_kilani_2021, title={Corrosion resistance and mechanical properties of Armakap cement for nuclear applications}, volume={374}, ISSN={["1872-759X"]}, DOI={10.1016/j.nucengdes.2021.111049}, abstractNote={Nuclear waste containers are prone to environmental degradation – over time, corrosion/erosion can cause the leakage of radioactive material which is a significant safety hazard. In the current work, environmental degradation of magnesium phosphate cement formulated by Armakap (2020, 3030) is investigated by using corrosion/erosion circulators that provide both acidic and saline environments. Test results indicate that Armakap formulations have reduced mass loss due to acidolysis by more than a factor of two in highly acidic conditions relative to a standard Portland cement sample. Additionally, the mechanical strength of Armakap 2020 formulation surpass that of Portland cement while Amrakap 3030 depicts a minor reduction. Although the Armakap 3030 provides good corrosion resistance, we conclude that Armakap 2020 shows optimal performance and is better suited than conventional Portland cement for a variety of nuclear waste storage applications at temperatures not exceeding 55 °C.}, journal={NUCLEAR ENGINEERING AND DESIGN}, author={Moneghan, Dan and Shkoukani, Ghada and Eapen, Jacob and Bourham, Mohammed and Mustafa, Walid and Kilani, Ramsey}, year={2021}, month={Apr} }
 @article{annamareddy_eapen_2021, title={Decoding ionic conductivity and reordering in cation-disordered pyrochlores}, volume={379}, ISSN={["1471-2962"]}, DOI={10.1098/rsta.2019.0452}, abstractNote={
            The ordered structure A
            2
            B
            2
            O
            6
            O’ in pyrochlores engenders twin rows of inequivalent anion sublattices each centred on alternating cations. While it is known that cation antisite disorder augments the ionic conductivity by several orders of magnitude, the local cation environment around the anions and the dynamic anion reordering during the cation disordering are not well-elucidated. Using atomistic simulations on Gd
            2
            Zr
            2
            O
            7
            , we first show that the anions engage in concerted hops to the neighbouring tetrahedral sites mostly along with the 〈1 0 0〉 direction while completely avoiding the octahedral sites. While the initially vacant 8
            a
            sites start accommodating oxygen ions with increasing cation disorder, they show noticeable reluctance even at significant levels of disorder. We have also tracked both the distribution of available oxygen sites following random cation disorder, which is dependent only on cation disordering, and the probability of occupation of these sites. Interestingly, the available oxygen sites show a non-monotonic dependence on the number of B ions in the nearest neighbouring shell while the occupation probability of all the available oxygen sites increases monotonically. A tetrahedral oxygen site thus has a better probability of being occupied when it has a greater number of second neighbour B ions.
          }, number={2211}, journal={PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES}, author={Annamareddy, Ajay and Eapen, Jacob}, year={2021}, month={Nov} }
 @article{raj_eapen_2019, title={Deducing Phonon Scattering from Normal Mode Excitations}, volume={9}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-019-43306-3}, abstractNote={Abstract}, journal={SCIENTIFIC REPORTS}, author={Raj, Anant and Eapen, Jacob}, year={2019}, month={May} }
 @article{raj_eapen_2019, title={Exact diagonal representation of normal mode energy, occupation number, and heat current for phonon-dominated thermal transport}, volume={151}, ISSN={["1089-7690"]}, DOI={10.1063/1.5099936}, abstractNote={Collective excitations of crystal vibrations or normal modes are customarily described using complex normal mode coordinates. While appropriate for calculating phonon dispersion, the mixed representation involving the complex conjugates does not allow the construction of equivalent phonon occupation number or modal dynamical quantities such as the energy or heat current specific to a wave-vector direction (q). Starting from a canonical solution that includes waves going to the left and right directions, we cast the Hamiltonian, normal mode population, and heat current in an exactly diagonalizable representation using real normal mode amplitudes. We show that the use of real amplitudes obviates the need for a complex modal heat current while making the passage to second quantization more apparent. Using nonequilibrium molecular dynamics simulations, we then compute the net modal energy, heat current, and equivalent phonon population in a linear lattice subjected to a thermal gradient. Our analysis paves a tractable path for probing and computing the direction-dependent thermal-phononic modal properties of dielectric lattices using atomistic simulations.}, number={10}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Raj, Anant and Eapen, Jacob}, year={2019}, month={Sep} }
 @article{raj_eapen_2019, title={Phonon dispersion using the ratio of zero-time correlations among conjugate variables: Computing full phonon dispersion surface of graphene}, volume={238}, ISSN={["1879-2944"]}, DOI={10.1016/j.cpc.2018.12.008}, abstractNote={We present a robust family of methods (ZTR) to compute the phonon dispersion curves based on the ratio of zero-time correlations of conjugate variables in the reciprocal space. This general technique extracts the normal mode frequency corresponding to wave vector q and polarization p, from the ratio of the correlation of the nth derivative of displacement to the n-1th derivative in reciprocal space at zero time. A particular version of this method using the ratio of velocity to displacement (n=1) is previously known but seldom employed in atomistic simulations. For n=2, the method involves velocities and accelerations — dynamical variables that are more well-defined than equilibrium displacements in atomistic simulations. We test the ZTR methods and demonstrate that both ZTR methods (n=1,2) can accurately resolve the phonon mode frequencies while offering a significant improvement to the computational speed. We also illustrate the ability of the ZTR methods to handle anharmonicity and phonon softening at high temperatures. Finally, we demonstrate the power of the ZTR approach by computing the full phonon dispersion surface for graphene across the entire Brillouin zone with 3600 wave vectors and six polarizations at finite temperatures — a challenging task for the traditional methods.}, journal={COMPUTER PHYSICS COMMUNICATIONS}, author={Raj, Anant and Eapen, Jacob}, year={2019}, month={May}, pages={124–137} }
 @article{mei_mohamed_eapen_2018, title={Approach to local thermodynamic equilibrium and the evolution to a glassy core following neutron/ion radiation impact}, volume={98}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2018.1502482}, abstractNote={ABSTRACT Using molecular dynamics simulations and statistical-mechanical metrics, we make quantitative predictions on the local thermodynamic and dynamic states following an ion or neutron impact in three materials – copper, silicon and solid argon. Through a two-energy distribution, we first capture the non-equilibrium temperature evolution and the approach to the local thermal equilibrium in three generic stages. By examining the time-resolved van Hove self-correlator, we then demonstrate that the impact core of all the three materials shows the dynamic characteristics of a jammed or glassy state. We delineate a dynamic atom-hopping mechanism that attests to a rapid defect recovery stage in copper; silicon, on the contrary, accommodates only small displacements which resist recovery. The dissimilitude between copper with a close-packed structure and silicon with an open network structure is further drawn out through an isoconfigurational analysis of displacements, which shows a compact dendritic-like condensation front for the mobile atoms in copper through atom hopping. In contrast, silicon portrays larger-scale spatial oscillations of dynamically separated regions, which appear to be a precursor to dynamic lattice instability and eventual amorphisation.}, number={29}, journal={PHILOSOPHICAL MAGAZINE}, author={Mei, Xiaojun and Mohamed, Walid and Eapen, Jacob}, year={2018}, pages={2701–2722} }
 @article{raj_eapen_2018, title={Computing Phonon Dispersion using Fast Zero-Point Correlations of Conjugate Variables}, volume={3}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2018.288}, abstractNote={Time correlations of dynamic variables in the reciprocal space offer a rich theoretical setting for computing the phonon dispersion curves, particularly for systems with marked anharmonic interactions. Present techniques primarily rely either on the equipartition of energy between the phonon modes or on the oscillation of the time correlation of the normal mode projections. The former can lead to numerical errors due to deviation from equipartition while the latter usually requires long simulations for computing the time correlations. We investigate a different approach using the ratio of the normal mode expectation value of two conjugate variables – velocity and acceleration. Since only the correlations at the initial time (t=0) are needed, this approach is computationally attractive. In this work, we employ this method to extract the full Brillouin zone phonon dispersion for graphene.}, number={10}, journal={MRS ADVANCES}, author={Raj, Anant and Eapen, Jacob}, year={2018}, pages={531–536} }
 @article{sanders_eapen_2018, title={Thermal Jamming of Ions in the Superionic State of UO2}, volume={3}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2018.326}, abstractNote={The oxygen ions in the high temperature superionic state of uranium dioxide (UO_2) are known to be in an arrested or jammed state, exhibiting characteristic features of jammed kinetics such as low dimensional string-like ion hopping and dynamical heterogeneity (DH). This thermally-jammed state entails a configurational entropic cost. Using atomistic simulations and the 2PT method, we compute the solid-like (vibrational) and hard sphere-like (configurational) contributions to the total entropy across a temperature range of 1500 K to 2800 K that envelop both the onset of superionic conduction (2000 K) and the second order λ-transition (2610 K). To properly account for the thermally jammed state of the ions, we use an equation of state that is appropriate for the metastable fluid branch. Our simulation results are in excellent agreement with the entropy data extracted from specific heat experiments with a mean error of less than 2%.}, number={31}, journal={MRS ADVANCES}, author={Sanders, Dillon and Eapen, Jacob}, year={2018}, pages={1777–1781} }
 @article{lowe_eapen_2018, title={Using Space-Time Correlations to Identify Transient Defects}, volume={3}, ISSN={["2059-8521"]}, DOI={10.1557/adv.2018.196}, abstractNote={Atomistic simulations are employed to investigate the dynamical behavior of atoms in cubic silicon carbide (SiC) following a 5 keV radiation knock. Specifically, we have computed the time-resolved van Hove self-correlation function, G_s(r,t), separately for the silicon and carbon sub-lattices. Our goal is to probe the early radiation damage mechanisms using a dynamical methodology. The simulation results show that the carbon atoms engage in a dynamic hopping mechanism as the system recovers from the radiation knock. The silicon atoms, however, exhibit a strikingly different behaviour: the time variation of 4πr^2G_s(r,t) indicates a dynamic tension between the crystalline and disordered regions of the Si sub-lattice. The power-law tail of the 4πr^2G_s(r,t) correlation for silicon atoms suggests a scale-free self-organized critical (SOC) state – a possible precursor to the collapse of the Si sub-lattice.}, number={31}, journal={MRS ADVANCES}, author={Lowe, William and Eapen, Jacob}, year={2018}, pages={1755–1760} }
 @article{annamareddy_eapen_2017, title={Disordering and dynamic self-organization in stoichiometric UO2 at high temperatures}, volume={483}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2016.10.042}, abstractNote={Neutron scattering experiments show significant oxygen disorder in UO2 at temperatures above 2000 K. The nature of the disorder, however, has not been ascertained with certainty. Using atomistic simulations and metrics from statistical mechanics we show that the oxygen anions predominantly hop from one native (tetrahedral) lattice site to another, above a characteristic temperature Tα (∼2000 K). Interestingly, we discover two types of disorder – the first one, which is a measure of the fraction of anions that are displaced from their native sites, portrays a monotonic increase with temperature and shows excellent conformity to neutron scattering data. The second metric based on the mean square displacement of the anions in an isoconfigurational ensemble demonstrates a dynamic self-organization behavior in which the anions are spatially correlated to those with similar mobility. This dynamic self-organization, however, experiences a non-monotonic variation with temperature depicting a maximum near the Bredig or λ-transition. We further establish that the thermodynamic metric cp/T, which is equal to the rate of change of entropy with temperature, is a key entropic indicator of the dynamic self-organization among the oxygen anions in UO2 at high temperatures.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Annamareddy, Ajay and Eapen, Jacob}, year={2017}, month={Jan}, pages={132–141} }
 @article{eapen_annamareddy_2017, title={Entropic crossovers in superionic fluorites from specific heat}, volume={23}, ISSN={["1862-0760"]}, DOI={10.1007/s11581-017-2007-z}, number={4}, journal={IONICS}, author={Eapen, Jacob and Annamareddy, Ajay}, year={2017}, month={Apr}, pages={1043–1047} }
 @article{annamareddy_eapen_2017, title={Ion hopping and constrained Li diffusion pathways in the superionic state of antifluorite Li2O}, volume={19}, number={5}, journal={Entropy}, author={Annamareddy, A. and Eapen, J.}, year={2017} }
 @article{annamareddy_eapen_2017, title={Low Dimensional String-like Relaxation Underpins Superionic Conduction in Fluorites and Related Structures}, volume={7}, ISSN={["2045-2322"]}, DOI={10.1038/srep44149}, abstractNote={Abstract}, journal={SCIENTIFIC REPORTS}, author={Annamareddy, Ajay and Eapen, Jacob}, year={2017}, month={Mar} }
 @article{sarkar_eapen_raj_murty_burchell_2016, title={Modeling irradiation creep of graphite using rate theory}, volume={473}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2016.01.036}, abstractNote={We have examined irradiation induced creep of graphite in the framework of transition state rate theory. Experimental data for two grades of nuclear graphite (H-337 and AGOT) have been analyzed to determine the stress exponent (n) and activation energy (Q) for plastic flow under irradiation. We show that the mean activation energy lies between 0.14 and 0.32 eV with a mean stress-exponent of 1.0 ± 0.2. A stress exponent of unity and the unusually low activation energies strongly indicate a diffusive defect transport mechanism for neutron doses in the range of 3–4 × 1022 n/cm2.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Sarkar, Apu and Eapen, Jacob and Raj, Anant and Murty, K. L. and Burchell, T. D.}, year={2016}, month={May}, pages={197–205} }
 @article{annamareddy_eapen_2015, title={Mobility propagation and dynamic facilitation in superionic conductors}, volume={143}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4933209}, DOI={10.1063/1.4933209}, abstractNote={In an earlier work [V. A. Annamareddy et al., Phys. Rev. E 89, 010301(R) (2014)], we showed the manifestation of dynamical heterogeneity (DH)—the presence of clustered mobile and immobile regions—in UO2, a model type II superionic conductor. In the current work, we demonstrate the mechanism of dynamic facilitation (DF) in two superionic conductors (CaF2 and UO2) using atomistic simulations. Using the mobility transfer function, DF is shown to vary non-monotonically with temperature with the intensity of DF peaking at temperatures close to the superionic transition temperature (Tλ). Both the metrics quantifying DH and DF show remarkable correspondence implying that DF, in the framework of kinematically constrained models, underpins the heterogeneous dynamics in type II superionic conductors.}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Annamareddy, Ajay and Eapen, Jacob}, year={2015}, month={Nov}, pages={194502} }
 @article{wang_chakraborty_eapen_2014, title={Absolute thermodynamic properties of molten salts using the two-phase thermodynamic (2PT) superpositioning method}, volume={16}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/C3CP52632A}, DOI={10.1039/C3CP52632A}, abstractNote={We show that the absolute thermodynamic properties of molten salts (mixtures of KCl and LiCl) can be accurately determined from the two-phase thermodynamic (2PT) method that is based on superpositioning of solid-like and gas-like (hard-sphere) vibrational density of states (DoS). The 2PT predictions are in excellent accordance with those from the thermodynamic integration method; the melting point of KCl evaluated from the free energy and the absolute entropy shows close conformity with the experimental/NIST data. The DoS partitioning shows that the Li(+) ions in the eutectic LiCl-KCl molten mixture are largely solid-like, unlike the K(+) and Cl(-) ions, which have a significant gas-like contribution, for temperatures ranging from 773 K to 1300 K. The solid-like states of the Li(+) ions may have practical implications when employed for chemical and nuclear reprocessing applications.}, number={7}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Wang, Jin and Chakraborty, Brahmananda and Eapen, Jacob}, year={2014}, pages={3062} }
 @article{sarkar_boopathy_eapen_murty_2014, title={Creep Behavior of Hydrogenated Zirconium Alloys}, volume={23}, ISSN={["1544-1024"]}, DOI={10.1007/s11665-014-1129-y}, number={10}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, author={Sarkar, A. and Boopathy, K. and Eapen, J. and Murty, K. L.}, year={2014}, month={Oct}, pages={3649–3656} }
 @article{annamareddy_nandi_mei_eapen_2014, title={Waxing and waning of dynamical heterogeneity in the superionic state}, volume={89}, ISSN={["1550-2376"]}, DOI={10.1103/physreve.89.010301}, abstractNote={Using molecular dynamics simulations of UO2-a type II superionic conductor-we identify a well-defined onset of dynamic disorder (Tα), which is remarkably correlated to a nontrivial advance of dynamical heterogeneity (DH). Quantified by the correlations in the dynamic propensity and van Hove self-correlation function, the DH is shown to grow with increasing temperature from Tα, peak at an intermediate temperature between Tα and Tλ-the superionic transition temperature-and then recede. Surprisingly, the DH attributes are not uniform across the temperatures-our investigation shows a low temperature (αT) stage DH, which is characterized by weak correlations and a plateaulike period in the correlations of the propensity, and a high temperature (λT) stage DH with strong correlations that are analogous to those in typical supercooled liquids. Our work, which has rigorously identified the onset of superionicity, gives a different direction for interpreting scattering experiments on the basis of statistical, correlated dynamics.}, number={1}, journal={PHYSICAL REVIEW E}, author={Annamareddy, V. Ajay and Nandi, Prithwish K. and Mei, Xiaojun and Eapen, Jacob}, year={2014}, month={Jan} }
 @article{mei_eapen_2013, title={Dynamic transitions in molecular dynamics simulations of supercooled silicon}, volume={87}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.87.134206}, abstractNote={Two dynamic transitions or crossovers, one at a low temperature (T∗ ≈ 1006 K) and the other at a high temperature (T0 ≈ 1384 K), are shown to emerge in supercooled liquid silicon using molecular dynamics simulations. The high-temperature transition (T0) marks the decoupling of stress, density, and energy relaxation mechanisms. At the low-temperature transition (T∗), depending on the cooling rate, supercooled silicon can either undergo a high-density-liquid to low-density-liquid (HDL-LDL) phase transition or experience an HDL-HDL crossover. Dynamically heterogeneous domains that emerge with supercooling become prominent across the HDL-HDL transition at 1006 K, with well-separated mobile and immobile regions. Interestingly, across the HDL-LDL transition, the most mobile atoms form large prominent aggregates while the least mobile atoms get spatially dispersed akin to that in a crystalline state. The attendant partial return to spatial uniformity with the HDL-LDL phase transition indicates a dynamic mechanism for relieving the frustration in supercooled states.}, number={13}, journal={PHYSICAL REVIEW B}, author={Mei, Xiaojun and Eapen, Jacob}, year={2013}, month={Apr} }
 @article{eapen_krishna_burchell_murty_2013, title={Early Damage Mechanisms in Nuclear Grade Graphite under Irradiation}, volume={2}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2013.841782}, DOI={10.1080/21663831.2013.841782}, abstractNote={Using Raman and X-ray photoelectron spectroscopy, we delineate the bond and defect structures in nuclear block graphite (NBG-18) under neutron and ion irradiation. The strengthening of the defect (D) peak in the Raman spectra under irradiation is attributed to an increase in the topological, sp2-hybridized defects. Using transmission electron microscopy, we provide evidence for prismatic dislocations as well as a number of basal dislocations dissociating into Shockley partials. The non-vanishing D peak in the Raman spectra, together with a generous number of dislocations, even at low irradiation doses, indicates a dislocation-mediated amorphization process in graphite.}, number={1}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Eapen, J. and Krishna, R. and Burchell, T. D. and Murty, K. L.}, year={2013}, month={Nov}, pages={43–50} }
 @article{chakraborty_wang_eapen_2013, title={Multicomponent diffusion in molten LiCl-KCl: Dynamical correlations and divergent Maxwell-Stefan diffusivities}, volume={87}, ISSN={["1550-2376"]}, DOI={10.1103/physreve.87.052312}, abstractNote={Multicomponent diffusional mechanisms in the ternary LiCl-KCl system are elucidated using the Green-Kubo formalism and equilibrium molecular dynamics simulations. The Maxwell-Stefan (MS) diffusion matrix is evaluated from the Onsager dynamical matrix that contains the diffusion flux correlation functions. From the temporal behavior of the correlation functions, we observe that the Li-Li and Li-Cl ion pairs have a pronounced cage dynamics that remains noticeably strong even at high temperatures. Even though the Onsager coefficients, which are the time integrals of the diffusion flux correlation functions, portray a relatively smooth variation across various compositions and temperatures, we observe a sign change and a divergent-like behavior for the MS diffusivity of the K-Li ion pair at a temperature of ~1100 K for the eutectic composition, and at a KCl mole fraction of ~0.49 at 1043 K. Negative MS diffusivities, while unusual, are however shown to satisfy the nonnegative entropic constraints.}, number={5}, journal={PHYSICAL REVIEW E}, author={Chakraborty, Brahmananda and Wang, Jin and Eapen, Jacob}, year={2013}, month={May} }
 @article{li_kushima_eapen_lin_qian_mauro_diep_yip_2011, title={Computing the viscosity of supercooled liquids: Markov network model}, volume={6}, number={3}, journal={PLoS One}, author={Li, J. and Kushima, A. and Eapen, J. and Lin, X. and Qian, X. F. and Mauro, J. C. and Diep, P. and Yip, S.}, year={2011} }
 @article{kushima_eapen_li_yip_zhu_2011, title={Time scale bridging in atomistic simulation of slow dynamics: viscous relaxation and defect activation}, volume={82}, ISSN={["1434-6036"]}, DOI={10.1140/epjb/e2011-20075-4}, number={3-4}, journal={EUROPEAN PHYSICAL JOURNAL B}, author={Kushima, A. and Eapen, J. and Li, Ju and Yip, S. and Zhu, T.}, year={2011}, month={Aug}, pages={271–293} }
 @article{burchell_murty_eapen_2010, title={Irradiation Induced Creep of Graphite}, volume={62}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-010-0145-0}, number={9}, journal={JOM}, author={Burchell, T. D. and Murty, K. L. and Eapen, J.}, year={2010}, month={Sep}, pages={93–99} }
 @article{eapen_rusconi_piazza_yip_2010, title={The classical nature of thermal conduction in nanofluids}, volume={132}, number={10}, journal={Journal of Heat Transfer}, author={Eapen, J. and Rusconi, R. and Piazza, R. and Yip, S.}, year={2010} }
 @article{buongiorno_venerus_prabhat_mckrell_townsend_christianson_tolmachev_keblinski_hu_alvarado_et al._2009, title={A benchmark study on the thermal conductivity of nanofluids}, volume={106}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.3245330}, DOI={10.1063/1.3245330}, abstractNote={This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.}, number={9}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Buongiorno, Jacopo and Venerus, David C. and Prabhat, Naveen and McKrell, Thomas and Townsend, Jessica and Christianson, Rebecca and Tolmachev, Yuriy V. and Keblinski, Pawel and Hu, Lin-wen and Alvarado, Jorge L. and et al.}, year={2009}, month={Nov}, pages={094312} }
 @article{kushima_lin_li_eapen_mauro_qian_diep_yip_2009, title={Computing the viscosity of supercooled liquids}, volume={130}, ISSN={["1089-7690"]}, DOI={10.1063/1.3139006}, abstractNote={We describe an atomistic method for computing the viscosity of highly viscous liquids based on activated state kinetics. A basin-filling algorithm allowing the system to climb out of deep energy minima through a series of activation and relaxation is proposed and first benchmarked on the problem of adatom diffusion on a metal surface. It is then used to generate transition state pathway trajectories in the potential energy landscape of a binary Lennard-Jones system. Analysis of a sampled trajectory shows the system moves from one deep minimum to another by a process that involves high activation energy and the crossing of many local minima and saddle points. To use the trajectory data to compute the viscosity we derive a Markov Network model within the Green–Kubo formalism and show that it is capable of producing the temperature dependence in the low-viscosity regime described by molecular dynamics simulation, and in the high-viscosity regime (102–1012 Pa s) shown by experiments on fragile glass-forming liquids. We also derive a mean-field-like description involving a coarse-grained temperature-dependent activation barrier, and show it can account qualitatively for the fragile behavior. From the standpoint of molecular studies of transport phenomena this work provides access to long relaxation time processes beyond the reach of current molecular dynamics capabilities. In a companion paper we report a similar study of silica, a representative strong liquid. A comparison of the two systems gives insight into the fundamental difference between strong and fragile temperature variations.}, number={22}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Kushima, Akihiro and Lin, Xi and Li, Ju and Eapen, Jacob and Mauro, John C. and Qian, Xiaofeng and Diep, Phong and Yip, Sidney}, year={2009}, month={Jun} }
 @article{kushima_lin_li_qian_eapen_mauro_diep_yip_2009, title={Computing the viscosity of supercooled liquids. II. Silica and strong-fragile crossover behavior}, volume={131}, ISSN={["1089-7690"]}, DOI={10.1063/1.3243854}, abstractNote={A recently developed atomistic method capable of calculating the fragile (non-Arrhenius) temperature behavior of highly viscous liquids is further tested by studying a model of SiO2, a glass former well known for its Arrhenius temperature behavior (strong). The method predicts an Arrhenius temperature variation, in agreement with experiments, the origin of which is revealed by both quantitative and qualitative results on transition state pathways, activation barrier analysis, energy landscape connectivity, and atomistic activation mechanisms. Also predicted is a transition from fragile to strong behavior at a lower viscosity, below the range of measurements, which had been previously suggested on the basis of molecular dynamics simulations. By systematically comparing our findings with corresponding results on the binary Lennard-Jones system (fragile) we gain new insights into the topographical features of the potential energy landscape, characteristics that distinguish strong from fragile glassy systems. We interpret fragility as a universal manifestation of slowing of dynamics when the system becomes trapped in deep energy basins. As a consequence, all glass-forming systems, when cooled from their normal liquid state, should exhibit two transitions in temperature scaling of the viscosity, a strong-to-fragile crossover followed by a second transition reverting back to strong behavior.}, number={16}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Kushima, Akihiro and Lin, Xi and Li, Ju and Qian, Xiaofeng and Eapen, Jacob and Mauro, John C. and Diep, Phong and Yip, Sidney}, year={2009}, month={Oct} }
 @inproceedings{eapen_2009, title={Thermal conduction mechanism in nanofluids, solid composites and liquid mixtures}, booktitle={HT2009: Proceedings of the ASME Summer Heat Transfer Conference 2009, vol 2}, author={Eapen, J.}, year={2009}, pages={163–167} }
 @article{keblinski_prasher_eapen_2008, title={Thermal conductance of nanofluids: is the controversy over?}, volume={10}, ISSN={1388-0764 1572-896X}, url={http://dx.doi.org/10.1007/S11051-007-9352-1}, DOI={10.1007/S11051-007-9352-1}, number={7}, journal={Journal of Nanoparticle Research}, publisher={Springer Science and Business Media LLC}, author={Keblinski, Pawel and Prasher, Ravi and Eapen, Jacob}, year={2008}, month={Jan}, pages={1089–1097} }