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Photo-induced lattice contraction in layered materials
摘要： Structural and electronic changes induced by optical excitation is a promising technique for functionalization of 2D crystals. Characterizing the effect of excited electronic states on the in-plane covalent bonding network as well as the relatively weaker out-of-plane dispersion interactions is necessary to tune photo-response in these highly anisotropic crystal structures. In-plane atom dynamics was measured using pump-probe experiments and characterized using ab initio simulations, but the effect of electronic excitation on weak out-of-plane van der Waals bonds is less well-studied. We use non-adiabatic quantum molecular dynamics to investigate atomic motion in photoexcited MoS2 bilayers. We observe a strong athermal reduction in the lattice parameter along the out-of-plane direction within 100 fs after electronic excitation, resulting from redistribution of electrons to excited states that have lesser anti-bonding character between layers. This non-trivial behavior of weakly bonded interactions during photoexcitation could have potential applications for modulating properties in materials systems containing non-covalent interactions like layered materials and polymers.
关键词： quantum molecular dynamics,layered materials,MoS2,photo-dynamics,van der Waals
更新于2025-09-23 15:22:29
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Thermodynamic, transport, and optical properties of dense silver plasma calculated using the GreeKuP code
摘要： The transport and optical properties of a dense silver plasma are calculated using our parallel GreeKuP code. The code uses the results of Vienna ab initio simulation package (VASP) as input information and is based upon the Kubo–Greenwood formula. The calculation is performed at the normal density 10.5 g/cm3 and 3 kK ≤ T ≤ 20 kK. Under these conditions, the results are strongly influenced by the presence of the d-electrons in silver: the real part of dynamic electrical conductivity has a non-Drude shape, the temperature dependence of thermal conductivity is non-monotonic, and the Wiedemann–Franz law is violated.
关键词： transport and optical properties,Kubo–Greenwood formula,GreeKuP code,quantum molecular dynamics
更新于2025-09-09 09:28:46