@article{nakhmanson_nardelli_bernholc_2004, title={Ab initio studies of polarization and piezoelectricity in vinylidene fluoride and BN-based polymers}, volume={92}, number={11}, journal={Physical Review Letters}, author={Nakhmanson, S. M. and Nardelli, M. B. and Bernholc, J.}, year={2004} }
 @article{fabian_feldman_hellberg_nakhmanson_2003, title={Numerical study of anharmonic vibrational decay in amorphous and paracrystalline silicon}, volume={67}, number={22}, journal={Physical Review. B, Condensed Matter and Materials Physics}, author={Fabian, J. and Feldman, J. L. and Hellberg, C. S. and Nakhmanson, S. M.}, year={2003}, pages={224302–1} }
 @article{nakhmanson_calzolari_meunier_bernholc_nardelli_2003, title={Spontaneous polarization and piezoelectricity in boron nitride nanotubes}, volume={67}, ISSN={["1098-0121"]}, DOI={10.1103/physrevb.67.235406}, abstractNote={Ab initio calculations of the spontaneous polarization and piezoelectric properties of boron nitride nanotubes show that they are excellent piezoelectric systems with response values larger than those of piezoelectric polymers. The intrinsic chiral symmetry of the nanotubes induces an exact cancellation of the total spontaneous polarization in ideal, isolated nanotubes of arbitrary indices. Breaking of this symmetry by intertube interaction or elastic deformations induces spontaneous polarization comparable to those of wurtzite semiconductors. order of magnitude weaker than those of PZT. 3 In this paper, we examine spontaneous polarization and piezoelectricity in boron nitride nanotubes ~BNNT's! in order to estimate their potential usefulness in various pyroelectric and piezoelectric device applications, and to understand the interplay between symmetry and polarization in nanotubular systems. BNNT's, broadly investigated since their initial predic- tion 4 and succeeding discovery, 5 are already well known for their excellent mechanical properties. 6 However, unlike car- bon nanotubes ~CNT's !, most of BN structures are noncen- trosymmetric and polar, which might suggest the existence of nonzero spontaneous polarization fields. Recently, these properties have been partially explored by Mele and Kral, using a model electronic Hamiltonian. 7 They predicted that BNNT's are piezoelectric and pyroelectric, with the direction of the spontaneous electric field that changes with the index of the tubes. The ab initio calculations presented in this pa- per provide a much fuller description and show that BNNT systems are indeed excellent lightweight piezoelectrics, with comparable or better piezoelectric response and superior me- chanical properties than in piezoelectric polymers. However, contrary to the conclusions of Ref. 7, our combined Berry phase and Wannier function ~WF! analysis demonstrates that electronic polarization in BNNT's does not change its direc- tion but rather grows monotonically with the increasing di- ameter of the tube. Furthermore, the electronic and ionic spontaneous polarizations in BNNT's cancel exactly and these systems are pyroelectric only if their intrinsic helical symmetry is broken by, e.g., intertube interactions or elastic distortions. The rest of this paper is organized as follows: Sec. II briefly reviews the formulation of the modern polarization theory in terms of Berry phases or Wannier functions. It also presents the details of the numerical techniques that were used to compute polarization. In Sec. III we discuss the re- sults and the complementary nature of the two techniques to compute the spontaneous polarization. Finally, Sec. IV pre- sents the summary and conclusions.}, number={23}, journal={PHYSICAL REVIEW B}, author={Nakhmanson, SM and Calzolari, A and Meunier, V and Bernholc, J and Nardelli, MB}, year={2003}, month={Jun} }
 @article{nakhmanson_drabold_mousseau_2002, title={Comment on 'Boson peak in amorphous silicon: A numerical study'}, volume={66}, number={8}, journal={Physical Review. B, Condensed Matter and Materials Physics}, author={Nakhmanson, S. M. and Drabold, D. A. and Mousseau, N.}, year={2002}, pages={087201–1} }
 @article{nakhmanson_mousseau_2002, title={Crystallization study of model tetrahedral semiconductors}, volume={14}, ISSN={["0953-8984"]}, DOI={10.1088/0953-8984/14/26/303}, abstractNote={The microscopic mechanisms leading to crystallization are not yet fully understood. This is due, in part, to the lack of atomistic as well as interatomic interaction models for a wide range of materials that can lead to crystallization on a computer-simulation timescale, i.e. < 100 ns. While the nucleation in close-packed systems has been extensively studied, there are almost no numerical results for covalent tetrahedral semiconductors. We present here the simulation results of crystallization from the liquid and amorphous states of a 1000-atom model of silicon, described with a modified Stillinger–Weber potential. With this potential, it is possible to crystallize the model in as little as a few nanoseconds, which opens a door to detailed studies of the nucleation processes in covalent systems. Using topological analysis, we also present a first characterization of the structural fluctuations of the nucleation centres in this system and give a rough estimate for the critical size of these centres.}, number={26}, journal={JOURNAL OF PHYSICS-CONDENSED MATTER}, author={Nakhmanson, SM and Mousseau, N}, year={2002}, month={Jul}, pages={6627–6638} }