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ABSTRACT
By combining the ab initio quantum mechanics (QM) calculation and the Drude model, electron temperature- and lattice temperature-dependent electron thermal conductivity is calculated and implemented into a multiscale model of laser material interaction, which couples the classical molecular dynamics (MD) and the two-temperature model (TTM). The results indicated that the electron thermal conductivity obtained from ab initio calculation leads to faster thermal diffusion than that using the electron thermal conductivity from empirical determination, which further induces a deeper melting region, a larger number of density waves travelling inside the copper film, and more various speeds of atomic clusters ablated from the irradiated film surface.
Nomenclature
| A | = | material constants describing the electron–electron scattering rate, s−1K−2 |
| B | = | material constants describing the electron–phonon scattering rate, s−1K−1 |
| Ce | = | electron heat capacity, J/(m3K) |
| E | = | energy, J |
| f | = | Fermi–Dirac distribution function |
| g | = | electron density of states |
| Ge−ph | = | electron–phonon coupling factor, W/(m3K) |
| J | = | laser fluence, J/cm2 |
| k | = | thermal conductivity, W/(mK) |
| kB | = | Boltzmann constant, 1.38 × 10−23J/K |
| L | = | penetrating depth, m |
| m | = | mass, kg |
| q | = | heat flux, W/m2 |
| ri | = | position of a nucleus |
| R | = | reflectivity |
| t | = | time, s |
| T | = | temperature, K |
| v | = | velocity, m/s |
| Vc | = | volume of unit cell, m3 |
| ε | = | electron energy level, J |
| μ | = | chemical potential, J |
| λ⟨ω2⟩ | = | second moment of the electron–phonon spectral function, meV2 |
| ρ | = | density, kg/m3 |
| τe | = | total electron scattering time |
| τxx | = | thermal stress, GPa |
| Subscripts and Superscripts | = | |
| e | = | electron |
| F | = | Fermi |
| l | = | lattice |
| op | = | optical |
| p | = | pulse |
| Acronyms and abbreviations widely used in text and list of references | = | |
| FDM | = | finite difference method |
| MD | = | molecular dynamics |
| QM | = | quantum mechanics |
| TTM | = | two-temperature model |
Nomenclature
| A | = | material constants describing the electron–electron scattering rate, s−1K−2 |
| B | = | material constants describing the electron–phonon scattering rate, s−1K−1 |
| Ce | = | electron heat capacity, J/(m3K) |
| E | = | energy, J |
| f | = | Fermi–Dirac distribution function |
| g | = | electron density of states |
| Ge−ph | = | electron–phonon coupling factor, W/(m3K) |
| J | = | laser fluence, J/cm2 |
| k | = | thermal conductivity, W/(mK) |
| kB | = | Boltzmann constant, 1.38 × 10−23J/K |
| L | = | penetrating depth, m |
| m | = | mass, kg |
| q | = | heat flux, W/m2 |
| ri | = | position of a nucleus |
| R | = | reflectivity |
| t | = | time, s |
| T | = | temperature, K |
| v | = | velocity, m/s |
| Vc | = | volume of unit cell, m3 |
| ε | = | electron energy level, J |
| μ | = | chemical potential, J |
| λ⟨ω2⟩ | = | second moment of the electron–phonon spectral function, meV2 |
| ρ | = | density, kg/m3 |
| τe | = | total electron scattering time |
| τxx | = | thermal stress, GPa |
| Subscripts and Superscripts | = | |
| e | = | electron |
| F | = | Fermi |
| l | = | lattice |
| op | = | optical |
| p | = | pulse |
| Acronyms and abbreviations widely used in text and list of references | = | |
| FDM | = | finite difference method |
| MD | = | molecular dynamics |
| QM | = | quantum mechanics |
| TTM | = | two-temperature model |