Thermodynamic functions of the heated electron subsystem in the field of cold nuclei

Sin'ko, G. V.; Smirnov, N. A.; Ovechkin, A. A.; Levashov, P. R.; Khishchenko, K. V.

doi:10.1016/j.hedp.2013.02.001

Cited by 43 publications

(17 citation statements)

References 36 publications

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“…Therefore, we use the electronic temperature dependent electron-phonon coupling and specific heats for bulk W, with G 0 calculated in previous work 58 and extrapolated to high T e following the methodology of Lin et al 59 . For low electronic temperatures, such as those encountered here, our calculated electronic specific heats are in ex- cellent agreement with Lin et al and more recent DFT studies [60][61][62] . The ionic subsystem is evolved in parallel with the electronic subsystem using classical MD.…”

Section: T-md Simulations Of Laser Irradiation Of W Thin Filmssupporting

confidence: 91%

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

et al. 2015

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The rearrangement of a material's electron density during laser irradiation leads to modified non-thermal forces on the atoms that may lead to coherent atomic motions and structural phase transformations on very short timescales. We present ab initio molecular dynamics simulations of a martensitic solid-solid phase transformation in tungsten under conditions of strong electronic excitation. The transformation is ultrafast, taking just over a picosecond, and follows the tetragonal Bain path. To examine whether a solid-solid bccfcc phase transformation could occur during laser irradiation, we use two-temperature molecular dynamics (2T-MD) simulations with a specially developed potential dependent on the electronic temperature. Our simulations show that the occurrence of the solid-solid phase transformation is in competition with ultrafast non-thermally assisted melting with the strength of the electron-phonon coupling determining the lifetime of the new solid phase. In tungsten the melting transition is predicted to occur too rapidly for the fcc phase to be detectable during laser irradiation.

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Section: T-md Simulations Of Laser Irradiation Of W Thin Filmssupporting

confidence: 91%

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

et al. 2015

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“…To investigate this problem we performed calculations for the pseudopotentials with different number of electrons beyond the core: with just one (2s 1 ) electron and with all electrons (1s 2 2s 1 ). In most experiments a natural lithium containing 2-3% of 6 Li is used; for this reason all calculations were carried out for 7 Li. The cut-off energy for the plane-wave basis was set to 600 eV for the 1-electron 7 Li pseudopotential while for the all-electron one the energy cut-offs for plane waves and augmented charges were chosen as 900 and 1700 eV, respectively.…”

Section: Methods and Parameters Of Calculationsmentioning

confidence: 99%

“…In most experiments a natural lithium containing 2-3% of 6 Li is used; for this reason all calculations were carried out for 7 Li. The cut-off energy for the plane-wave basis was set to 600 eV for the 1-electron 7 Li pseudopotential while for the all-electron one the energy cut-offs for plane waves and augmented charges were chosen as 900 and 1700 eV, respectively. The radius of the invariable core ðR CORE Þ of the 1-electron pseudopotential for lithium was 2.05 Bohr (1.085 Å) and for the all-electron one-1.5 Bohr (0.794 Å); the core radius of the pseudopotential for hydrogen was 1.1 Bohr (0.582 Å).…”

Section: Methods and Parameters Of Calculationsmentioning

confidence: 99%

“…The electronic temperature was fixed through the Fermi-Dirac distribution and the ionic one was maintained by the Nosé-Hoover thermostat [37], T e ¼ T i ¼ T in all calculations. Thermodynamic properties of 7 LiD with the 1-electron Li pseudopotential were obtained for a cubic supercell containing 108 atoms of 7 Li and 108 atoms of D. Simulations with the all-electron Li pseudopotential employed also 108 molecules of 7 LiD for low pressure calculations and 32 molecules of 7 LiD at q > 2:0 g/cm 3 .…”

Section: Methods and Parameters Of Calculationsmentioning

confidence: 99%

“…High accuracy of models themselves as well as high accuracy of computations are required to confidently establish an observed effect (see, for example, the discussion concerning the electronic topological transition in zinc [2,3], and s-d transition in alkali metals [4,5]). Recently, it was found out that the excitation of inner electrons in crystals under compression or heating significantly contributed to the electronic heat capacity, but had only weak influence on the electronic pressure [6,7]. These facts were stated in density functional theory (DFT) calculations by both full-potential and pseudopotential methods.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic properties of LiD under compression with different pseudopotentials for lithium

Minakov

Levashov

2016

Computational Materials Science

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Electron‐Ion Relaxation, Phase Transitions, and Surface Nano‐Structuring Produced by Ultrashort Laser Pulses in Metals

Inogamov

Zhakhovsky

Petrov

et al. 2013

Contrib. Plasma Phys.

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Fundamental physical phenomena in metals irradiated by ultrashort laser pulses with absorbed fluences higher than few tens of mJ/cm2 are investigated. For those fluences, laser‐produced electron distribution function relaxes to equilibrium Fermi distribution with electron temperature Te within a short time of 10‐100 fs. Because the electron subsystem has Te highly exceeding much the ion subsystem temperature Ti the well‐known twotemperature hydrodynamic model (2T‐HD) is used to evaluate heat propagation associated with hot conductive electron diffusion and electron‐ion energy exchange. The model coefficients of electron heat conductivity κ (ϱ, Te, Ti) and electron‐ion coupling parameter α (ϱ, Te) together with 2T equation of state E (ϱ, Te, Ti) and P (ϱ, Te, Ti) are calculated. Modeling with 2T‐HD code shows transition of electron heat wave from supersonic to subsonic regime of prop‐agation. At the moment of transition the heat wave emits a compression wave moving into the bulk of met al. Nonlinear evolution of the compression wave after its separation from the subsonic heat wave till spallation of rear‐side layer of a film is traced in both 2T‐HD modeling and molecular dynamics (MD) simulation. For fluences above some threshold the nucleation of voids in frontal surface layer is initiated by strong tensile wave following the compression wave. If the absorbed fluence is ∼30 % above the ablation threshold than void nucleation develops quickly to heavily foam the molten met al. Long‐term evolution of the metal foam including foam breaking and freezing is simulated. It is shown that surface nano‐structures observed in experiments are produced by very fast cooling of surface molten layer followed by recrystallization of supercooled liquid in disintegrating foam having complex geometry. Characteristic lengths of such surface nanostructures, including frozen pikes and bubbles, are of the order of thickness of molten layer formed right after laser irradiation. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Thermodynamic functions of the heated electron subsystem in the field of cold nuclei

Cited by 43 publications

References 36 publications

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

Dynamical simulations of an electronically induced solid-solid phase transformation in tungsten

Thermodynamic properties of LiD under compression with different pseudopotentials for lithium

Electron‐Ion Relaxation, Phase Transitions, and Surface Nano‐Structuring Produced by Ultrashort Laser Pulses in Metals

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