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Author Sun, Huayang ♦ Kang, Dongdong ♦ Dai, Jiayu ♦ Ma, Wen ♦ Zhou, Liangyuan ♦ Zeng, Jiaolong
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY ♦ COMPRESSION ♦ CORRECTIONS ♦ DENSITY FUNCTIONAL METHOD ♦ ELECTRIC POTENTIAL ♦ ELECTRONIC STRUCTURE ♦ EQUATIONS OF STATE ♦ EXPERIMENTAL DATA ♦ MOLECULAR DYNAMICS METHOD ♦ TEMPERATURE DEPENDENCE ♦ VAN DER WAALS FORCES
Abstract The equation of states (EOS) and electronic structures of argon with temperatures from 0.02 eV to 3 eV and densities from 0.5 g/cm{sup 3} to 5.5 g/cm{sup 3} are calculated using the pair potential and many-body potential molecular dynamics and the density functional theory (DFT) molecular dynamics with van der Waals (vdW) corrections. First-principles molecular dynamics is implemented above 2.0 g/cm{sup 3}. For the cases of low densities below 3 g/cm{sup 3}, we performed pair potential molecular dynamics in order to obtain the ionic configurations, which are used in density functional theory to calculate the EOS and electronic structures. We checked the validity of different methods at different densities and temperatures, showing their behaviors by comparing EOS. DFT without vdW correction works well above 1 eV and 3.5 g/cm{sup 3}. Below 1 eV and 2.0 g/cm{sup 3}, it overestimates the pressure apparently and results in incorrect behaviors of the internal energy. With vdW corrections, the semi-empirical force-field correction (DFT-D2) method gives consistent results in the whole density and temperature region, and the vdW density functional (vdW-DF2) method gives good results below 2.5 g/cm{sup 3}, but it overestimates the pressure at higher densities. The interactions among the atoms are overestimated by the pair potential above 1 eV, and a temperature dependent scaled pair potential can be used to correct the ionic configurations of the pair potential up to 3 eV. The comparisons between our calculations and the experimental multi-shock compression results show that the Hugoniot line of DFT-D2 and DFT tends to give larger pressure than the results of the self-consistent fluid variational theory, and the difference increases with the density. The electronic energy gap exists for all our cases up to 5.5 g/cm{sup 3} and 1 eV. The effect of vdW interactions on the electronic structures are also discussed.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-03-28
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 144
Issue Number 12


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