arXiv subjects

Fedor Akhmetov

Publications and source records attributed to Fedor Akhmetov.

3 recordsLinked to original sources

arXiv2023

Electronic heat conductivity in a two-temperature state

Laser irradiation of materials is most commonly modeled with the two-temperature model (TTM), or its combination with molecular dynamics, TTM-MD. For such modeling, the electronic transport coefficients are required. Here, we calculate the electronic heat conductivity at elevated electron temperatures up to 40,000 K. We apply the tight binding formalism to calculate the electron-phonon contribution to the electronic heat conductivity, and the linear response theory (in the single-pole Ritchie-Howie loss function approximation) for its electron-electron counterpart, implemented in the hybrid code XTANT-3. It allows us evaluation of the electronic heat conductivity in a wide range of materials - fcc metals: Al, Ca, Ni, Cu, Sr, Y, Zr, Rh, Pd, Ag, Ir, Pt, Au, and Pb; hcp metals: Mg, Sc, Ti, Co, Zn, Tc, Ru, Cd, Hf, Re, and Os; bcc metals: V, Cr, Fe, Nb, Mo, Ba, Ta, and W; other metals: Sn, Ga, In, Mn, Te, and Se; semimetal graphite; semiconductors - group IV: Si, Ge, and SiC; group III-V: AlAs, AlP, GaP, GaAs, and GaSb; oxides: ZnO, TiO$_2$, and Cu$_2$O; and others: PbI$_2$, ZnS, and B$_4$C.

cond-mat.mtrl-sci↗

arXiv2022

Laser-induced electron dynamics and surface modification in ruthenium thin films

We performed the experimental and theoretical study of the heating and damaging of ruthenium thin films induced by femtosecond laser irradiation. Results of an optical pump-probe thermoreflectance experiment with rotating sample allowing to significantly reduce heat accumulation in irradiated spot are presented. We show the evolution of surface morphology from growth of a heat-induced oxide layer at low and intermediate laser fluences to cracking and grooving at high fluences. Theoretical analysis of pump-probe signal allows us to relate behavior of hot electrons in ruthenium to the Fermi smearing mechanism. The analysis of heating is performed with the two-temperature modeling and molecular dynamics simulation, results of which demonstrate that the calculated melting threshold is higher than experimental damage threshold. We attribute it to heat-induced surface stresses leading to cracking which accumulates to more severe damage morphology. Our results provide an upper limit for operational conditions for ruthenium optics and also direct to further studies of the Fermi smearing mechanism in other transition metals.

cond-mat.mtrl-sci↗

arXiv2018

Gene expression for simulation of biological tissue

BioDynaMo is a biological processes simulator developed by an international community of researchers and software engineers working closely with neuroscientists. The authors have been working on gene expression, i.e. the process by which the heritable information in a gene - the sequence of DNA base pairs - is made into a functional gene product, such as protein or RNA. Typically, gene regulatory models employ either statistical or analytical approaches, being the former already well understood and broadly used. In this paper, we utilize analytical approaches representing the regulatory networks by means of differential equations, such as Euler and Runge-Kutta methods. The two solutions are implemented and have been submitted for inclusion in the BioDynaMo project and are compared for accuracy and performance.

q-bio.QM↗