Structural and vibrational properties of solid nitromethane under high pressure by density functional theory J. Chem. Phys. 124, 124501 (2006); 10.1063/1.2179801 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation. The geometrical structures of the crystalline polyethylene under several different external pressures up to 10 GPa are optimized by a pseudopotential plane wave density functional method. Both local density ͑LDA͒ and generalized gradient ͑GGA͒ approximations for exchange-correlation energy and potential are used. It is found that LDA heavily underestimate the geometry parameters under ambient pressure but GGA successfully correct them and get results in good agreements with the experimental geometry. The calculated GGA volume is about 94 Å 3 in comparison with the x-ray scattering value of about 92 Å 3 and the neutron scattering value of 88 Å 3 . The bulk and Young's modulus are calculated by means of several different methods. The Young's modulus along the chain ranges from about 350 to about 400 GPa which is in good agreement with the experimental results. But the bulk modulus is several times larger than those of experiments, indicating a different description of the interchain interactions by both LDA and GGA. The band structures are also calculated and their changes with the external pressure are discussed.
Articles you may be interested inAb initio calculation of the CdSe/CdTe heterojunction band offset using the local-density approximation-1/2 technique with spin-orbit corrections J. Appl. Phys. 111, 073708 (2012) All-electron first-principles total energy electronic structure calculations were carried out for single chains of four nucleotide base stacks ͑composed of adenine, thymine, guanine, and cytosine, respectively͒ in the DNA B conformation ͑3.36 Å stacking distance and 36°screw angle ͒ using the local-density approximation ͑LDA͒ within a helical band structure approach. A uracil stack was also computed in the DNA B conformation and compared with the results obtained for the four DNA base stacks. The total energies per unit cell as a function of the stacking distance ͑at fixed screw angle ϭ36°͒ and of the screw angle ͑at dϭ3.36 Å͒ show in most cases rather good agreement with the experiment. As expected with LDA calculations, the band gaps were underestimated by nearly 50% compared to experimentally suggested values. Finally, some suggestions are given for the improvement of the band structures of the nucleotide base stacks.
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