Thermodynamic properties of LiD under compression with different pseudopotentials for lithium

Minakov, D. V.; Levashov, P. R.

doi:10.1016/j.commatsci.2015.12.008

Cited by 24 publications

(3 citation statements)

References 38 publications

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“…9. Experimental results compared to previous measurements from the Z machine [51], from gas guns [38] and from underground tests [39,53]; theoretical predictions from QMD (this work, in close agreement with [51,52,58] and density functional theory [59]; and tabulated equation of state models [58,61]. Precompressed data points are shown as diamondshaped red symbols FIG.…”

Section: Resultsmentioning

confidence: 62%

Shock equation of state of LiH6 to 1.1 TPa

et al. 2017

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Using laser-generated shock waves, we have measured pressure, density and temperature of LiH on the principal Hugoniot between 260 and 1100 GPa (2.6-11 Mbar) and on a second-shock Hugoniot up to 1400 GPa to near 5-fold compression, extending the maximum pressure reached in non-nuclear experiments by a factor of two. We observe the onset of metal-like reflectivity consistent with temperature-induced ionization of the Li 2s electron, and no sign of additional changes in ionization up to the maximum pressure. Our measurements are in good agreement with gas gun, Z-machine and underground test data and are accurately described by quantum molecular dynamics simulations. The results confirm the validity of equation of state models built on an average-atom description of the electron-thermal contribution to the free energy and a density-dependent Grüneisen parameter to describe shock response of LiH over this pressure range.

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Section: Resultsmentioning

confidence: 62%

Shock equation of state of LiH6 to 1.1 TPa

et al. 2017

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“…As some electrons in a pseudopotential DFT approach are included into an invariable core this method is restricted both on temperature and density because of the excitation of core electrons [31]. Also in QMD additional error may appear when some particles move very close to each other at high enough temperatures [32]. Therefore the validity of each pseudopotential should be checked at given simulation conditions.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Influence of shell effects on thermodynamic properties of matter at high pressures

Levashov

Minakov

2018

J. Phys.: Conf. Ser.

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Abstract. We analyze the influence of shell effects on thermodynamic properties of matter at high pressures. Spherically symmetric average atom models show significant contribution of electronic transitions to cold pressure which is not confirmed by more accurate density functional theory models. In particular, the s-d transition in aluminum and potassium does not reveal itself on the shock Hugoniots. Oscillations on shock Hugoniots at very high pressures predicted earlier by many authors should be confirmed by precise first-principle calculations. IntroductionThermodynamic properties of matter at high pressure are of importance in many problems of high energy density physics, in particular, in astrophysics [1], in wide-range equations of state [2,3], in the problems of interaction of intense energy fluxes with matter [4-6], in perspective power generation facilities [7] and in some others. The finite-temperature Thomas-Fermi (TF) model [8] based upon semiclassical approximation is widely used to describe thermodynamic properties of matter, but there are many phenomena beyond this approach. In particular, shell effects reflect non-regularities of physical parameters because of the discrete energy spectrum. For example, in low-density plasma step-wise dependencies of thermodynamic functions on isochors or isobars are quite typical [9]. The other well-known effect is connected with the non-regular behavior of density of elements vs. atomic mass [10,11]. To describe shell effects one should take into account discrete energy levels. Analytically shell corrections to the TF model have been studied in [12,13] using the Poisson formula in the transition from summation to integration (see also the review [14]). Average atom models [15][16][17][18][19] are based on a radial solution of the single-particle Schrödinger (Dirac) equation so that the discrete spectrum and shell effects are taken into account implicitly. During the last 30 years it became possible to obtain approximate three-dimensional (3D) solutions of a quantum many-particle problem using density functional theory (DFT) [20,21]. In this case one gets a 3D band structure of a system of particles that provides for the appearance of shell effects through non-regularities of the electronic density and some thermodynamic functions. There were several attempts to register shell effects at high pressures and temperatures experimentally [22][23][24] using underground nuclear explosions. It is claimed [24] that the influence of the discrete energy spectrum is

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“…Recently, Kulsartov et al [20] have experimentally studied the T release processes from two-phase Li ceramics of Li 4 SiO 4 /Li 2 TiO 3 during neutron irradiation when H and D are injected into the chamber with irradiated samples, and found a preferential increase in the release of DT molecules when the pressure of D in the gas phase increases. In addition, the design and construction of corresponding high-energy neutron source, in which D 6 Li [27][28][29][30][31][32][33] is a potential fuel option, is also greatly important to solve the problems of nuclear fuel cycle circuit and positive energy gain of future clean energy systems. Such systems has been suggested as drivers of hybrid fusion-fission reactors for nuclear power generation and production of T.…”

Section: Introductionmentioning

confidence: 99%

Energy loss of α-particle in the non-equilibrium plasma of deuterium mixed with lithium

Fu¹,

Gao²,

Mo³

et al. 2022

Nucl. Fusion

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The stopping power of compressed and highly ionized deuterium (D) plasma mixed with lithium (Li), in which the electron and ion temperatures are non-equilibrium (i.e., Te≠Ti), to the injected α-particles is studied. Wide ranges of temperature (0.5 keV∼10 keV) and density (1 g/cm3∼500 g/cm3) of D-Li mixing plasmas are considered. The numerical results show that, in the temperature equilibrium state, the change ratio of stopping power (denoted by η) increases positively with the increase of the fraction of Li (denoted by xLi). However, in some non-equilibrium dense plasma states, η may increase negatively with the increase of xLi. The corresponding nonlinear response of η to xLi may become more (less) remarkable if Ti>Te ( Ti <Te), which suggests that the collective excitation in the stopping power of D-Li mixing plasmas in which Ti>Te ( Ti <Te) will be enhanced (suppressed) due to the non-equilibrium temperature effect. As a result, the change ratio of deposition depth of α-particles (denoted by χ) for the non-equilibrium case of Te>Ti rather than Ti>Te seems to be closer to that of equilibrium cases. Furthermore, our results show that more than 60% of energy of injected α-particles is deposited into the electron species, and the energy deposited into the electron component (Ee/E0) is a monotonic decay function of xLi. In addition, relative to the equilibrium results, we find that Ee/E0 will slightly increase (decrease) when Ti>Te (Te>Ti). The findings and analysis in this work indicate that the non-equilibrium implosion with Te>Ti may be more controllable than that with Ti>Te, which may be useful for the advanced development of fusion propulsion systems, in which DLi is a potential fuel option.

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Thermodynamic properties of LiD under compression with different pseudopotentials for lithium

Cited by 24 publications

References 38 publications

Shock equation of state of LiH6 to 1.1 TPa

Shock equation of state of LiH6 to 1.1 TPa

Influence of shell effects on thermodynamic properties of matter at high pressures

Energy loss of α-particle in the non-equilibrium plasma of deuterium mixed with lithium

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