@article{tichnell_miller_liu_mukherjee_jakubikova_mccusker_2020, title={Influence of Electrolyte Composition on Ultrafast Interfacial Electron Transfer in Fe-Sensitized TiO2-Based Solar Cells}, volume={124}, ISSN={["1932-7455"]}, DOI={10.1021/acs.jpcc.9b09404}, abstractNote={TiO2-based dye-sensitized solar cells employing Fe(2,2′-bipyridine-4,4′-dicarboxylic acid)2(CN)2 (F2CA) have been studied by spectroscopic, electrochemical, photoelectrochemical, time-resolved spec...}, number={3}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Tichnell, Christopher R. and Miller, Jennifer N. and Liu, Chang and Mukherjee, Sriparna and Jakubikova, Elena and McCusker, James K.}, year={2020}, month={Jan}, pages={1794–1811} }
 @article{qiao_liu_gao_huang_2019, title={Graphene oxide model with desirable structural and chemical properties}, volume={143}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2018.11.063}, abstractNote={Due to unique chemical, electrical and optical properties, graphene oxide has been widely used as a promising candidate for many applications. Theoretical GO models developed so far present a good description of its chemical structure. However, when it comes to the structural properties, such as the size and distribution of vacancy defects, the curvature (or roughness), there exist significant gaps between computational models and experimentally synthesized GO materials. In this work, we carry out reactive molecular dynamics simulations and use experimental characteristics to fine tune theoretical GO models. Attentions have been paid to the vacancy defects, the distribution and hybridization of carbon atoms, and the overall C/O ratio of GO. The GO models proposed in this work have been significantly improved to represent quantitative structural details of GO materials synthesized via the modified Hummers method. The temperature-programmed protocol and the computational post analyses of Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, vacancy size and curvature distribution, are of general interest to a broad audience working on GO structures from other synthesis methods and other two-dimensional materials and their composites.}, journal={CARBON}, author={Qiao, Qi and Liu, Chang and Gao, Wei and Huang, Liangliang}, year={2019}, month={Mar}, pages={566–577} }
 @article{liu_kelley_jakubikova_2019, title={Molecular Dynamics Simulations on Relaxed Reduced-Dimensional Potential Energy Surfaces}, volume={123}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/acs.jpca.9b02298}, DOI={10.1021/acs.jpca.9b02298}, abstractNote={Molecular dynamics (MD) simulations with full-dimensional potential energy surfaces (PESs) obtained from high-level ab initio calculations are frequently used to model reaction dynamics of small molecules (i.e., molecules with up to 10 atoms). Construction of full-dimensional PESs for larger molecules is, however, not feasible since the number of ab initio calculations required grows rapidly with the increase of dimension. Only a small number of coordinates are often essential for describing the reactivity of even very large systems, and reduced-dimensional PESs with these coordinates can be built for reaction dynamics studies. While analytical methods based on transition-state theory framework are well established for analyzing the reduced-dimensional PESs, MD simulation algorithms capable of generating trajectories on such surfaces are more rare. In this work, we present a new MD implementation that utilizes the relaxed reduced-dimensional PES for standard microcanonical (NVE) and canonical (NVT) MD simulations. The method is applied to the pyramidal inversion of a NH3 molecule. The results from the MD simulations on a reduced, three-dimensional PES are validated against the ab initio MD simulations, as well as MD simulations on full-dimensional PES and experimental data.}, number={21}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={Liu, Chang and Kelley, C. T. and Jakubikova, Elena}, year={2019}, month={Apr}, pages={4543–4554} }
 @article{britz_gawelda_assefa_jamula_yarranton_galler_khakhulin_diez_hardee_doumy_et al._2019, title={Using Ultrafast X-ray Spectroscopy To Address Questions in Ligand-Field Theory: The Excited State Spin and Structure of [Fe(dcpp)(2)](2+)}, volume={58}, ISBN={1520-510X}, DOI={10.1021/acs.inorgchem.9b01063}, abstractNote={We have employed a range of ultrafast X-ray spectroscopies in an effort to characterize the lowest energy excited state of [Fe(dcpp)2]2+ (where dcpp is 2,6-(dicarboxypyridyl)pyridine). This compound exhibits an unusually short excited-state lifetime for a low-spin Fe(II) polypyridyl complex of 270 ps in a room-temperature fluid solution, raising questions as to whether the ligand-field strength of dcpp had pushed this system beyond the 5T2/3T1 crossing point and stabilizing the latter as the lowest energy excited state. Kα and Kβ X-ray emission spectroscopies have been used to unambiguously determine the quintet spin multiplicity of the long-lived excited state, thereby establishing the 5T2 state as the lowest energy excited state of this compound. Geometric changes associated with the photoinduced ligand-field state conversion have also been monitored with extended X-ray absorption fine structure. The data show the typical average Fe-ligand bond length elongation of ∼0.18 Å for a 5T2 state and suggest a high anisotropy of the primary coordination sphere around the metal center in the excited 5T2 state, in stark contrast to the nearly perfect octahedral symmetry that characterizes the low-spin 1A1 ground state structure. This study illustrates how the application of time-resolved X-ray techniques can provide insights into the electronic structures of molecules-in particular, transition metal complexes-that are difficult if not impossible to obtain by other means.}, number={14}, journal={INORGANIC CHEMISTRY}, author={Britz, Alexander and Gawelda, Wojciech and Assefa, Tadesse A. and Jamula, Lindsey L. and Yarranton, Jonathan T. and Galler, Andreas and Khakhulin, Dmitry and Diez, Michael and Hardee, Manuel and Doumy, Gilles and et al.}, year={2019}, pages={9341–9350} }
 @article{mukherjee_liu_jakubikova_2018, title={Comparison of Interfacial Electron Transfer Efficiency in [Fe(ctpy)(2)](2+)-TiO2 and [Fe(cCNC)(2)](2+)-TiO2 Assemblies: Importance of Conformational Sampling}, volume={122}, ISSN={["1089-5639"]}, DOI={10.1021/acs.jpca.7b10932}, abstractNote={Fe(II)-polypyridines have limited applications as chromophores in dye-sensitized solar cells due to the short lifetimes (∼100 fs) of their photoactive metal-to-ligand charge transfer (MLCT) states formed upon photoexcitation. Recently, a 100-fold increase in the MLCT lifetime was observed in a [Fe(CNC)2]2+ complex (CNC = 2,6-bis(3-methylimidazole-1-ylidine)pyridine) which has strong σ-donating N-heterocyclic carbene ligand in comparison to the weaker field parent [Fe(tpy)2]2+ complex (tpy = 2,2':6',2″-terpyridine). This study utilizes density functional theory (DFT), time-dependent DFT, and quantum dynamics simulations to investigate the interfacial electron transfer (IET) in [Fe(cCNC)2]2+ (cCNC = 4'-carboxy-2,6-bis(3-methylimidazole-1-ylidine)pyridine) and [Fe(ctpy)2]2+ (ctpy = 4'-carboxy-2,2':6',2″-terpyridine) sensitized TiO2. Our results suggest that the replacement of tpy by CNC ligand does not significantly speed up the IET kinetics in the [Fe(cCNC)2]2+-TiO2 assembly in comparison to the [Fe(ctpy)2]2+-TiO2 analogue. The high IET efficiency in the [Fe(cCNC)2]2+-TiO2 assemblies is therefore due to longer lifetime of [Fe(cCNC)2]2+ photoactive 3MLCT states rather than faster electron injection kinetics. It was also found that the inclusion of conformational sampling in the computational model is important for proper description of the IET processes in these systems, as the models relying on the use of only fully optimized structures may yield misleading results. The simulations presented in this work also illustrate various pitfalls of utilizing properties such as electronic coupling, number of available acceptor states, and driving force, as well as calculations based on Fermi's golden rule framework, to reach conclusions on the IET efficiency in dye-semiconductor systems.}, number={7}, journal={JOURNAL OF PHYSICAL CHEMISTRY A}, author={Mukherjee, Sriparna and Liu, Chang and Jakubikova, Elena}, year={2018}, month={Feb}, pages={1821–1830} }
 @article{liu_jakubikova_2017, title={Two-step model for ultrafast interfacial electron transfer: limitations of Fermi's golden rule revealed by quantum dynamics simulations}, volume={8}, ISSN={["2041-6539"]}, DOI={10.1039/c7sc01169e}, abstractNote={A two-step model of interfacial electron transfer is proposed along with a practical approach to screening dye-sensitizers based on a calculation of the percentage of electron density on the linker group and the number of available semiconductor acceptor states.}, number={9}, journal={CHEMICAL SCIENCE}, author={Liu, Chang and Jakubikova, Elena}, year={2017}, month={Sep}, pages={5979–5991} }