Thermodynamic properties of LiD under compression with different pseudopotentials for lithium

[Display omitted] •We study thermodynamics of LiD at high pressures and temperatures.•Calculations with 1 valence electron for Li underestimate pressure on LiD Hugoniot.•We detect weaker repulsion of Li ions with a frozen inner shell.•We obtain new data on double shock compression of 7LiD up to 1.2T...

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Bibliographic Details
Published in:Computational materials science 2016-03, Vol.114, p.128-134
Main Authors: Minakov, D.V., Levashov, P.R.
Format: Article
Language:English
Subjects:
Ab initio
Compressing
Data compression
Density functional theory
Frozen
Lithium
Lithium deuteride hugoniot
Mathematical analysis
Pseudopotential core
Pseudopotentials
Quantum molecular dynamics
Thermodynamic properties
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Summary:[Display omitted] •We study thermodynamics of LiD at high pressures and temperatures.•Calculations with 1 valence electron for Li underestimate pressure on LiD Hugoniot.•We detect weaker repulsion of Li ions with a frozen inner shell.•We obtain new data on double shock compression of 7LiD up to 1.2TPa.•Overlapping of cores limits the application of pseudopotentials for unordered state. We analyze the contribution of the inner-shell electrons of Li and overlapping of pseudopotential cores to thermodynamic properties of 7LiD under compression using density functional theory and quantum molecular dynamics. At zero temperature there is no noticeable influence of 1s electrons of Li on pressure up to fivefold compression. However, shock compression reveals significant difference in pressure in calculations with 1 or 3 valence electrons for Li at pressures higher than 200GPa. This fact can be explained by the weaker repulsion of Li ions with the frozen inner shell rather than by the excitation of the inner-shell electrons. We estimate conditions at which the one-electron pseudopotential is inapplicable in the unordered phase. Also we obtain new data on double shock compression of 7LiD up to 1.2TPa in good agreement with available experiments.
ISSN:0927-0256
1879-0801
DOI:10.1016/j.commatsci.2015.12.008