Nonadiabatic processes

nonadiabatic_processes sets the option to simulate the non-equilibrium phenomena, for example under a radiation cascade, where the electronic stopping and electronic-phonon coupling in the later stages of the event will be taken into account according to the eph model [[1]]. MD for the atoms is performed through the use of Langevin dynamics where the random and friction forces are related through the fluctuation-dissipation theorem. Here the random and friction forces are given as tensor functions of atomic postions. The electronic system is considered as a mesh in three dimension and electronic temperature is calculated along with MD by solving the heat diffusion equation using finite difference method. There are twenty input keywords connected to this calculation method. For some of these keywords input may or may not be provided always. These are as follows:

eph_fdm_option, eph_friction_option, eph_random_option, eph_betafile, eph_Tinfile, eph_box_limits, eph_rho_e, eph_C_e, eph_kappa_e, eph_Ti_e, eph_gsx, eph_gsy, eph_gsz, eph_fdm_steps, eph_md_last_step, eph_md_prev_time, eph_E_prev_time, eph_freq_Tout, eph_freq_mesh_Tout, eph_Toutfile

Summary

Summary for nonadiabatic_processes keyword

Required/optional	Type	Accepted values	Default	See also	Remarks
Optional	Boolean	.true. or .false.	.false.	electronic_stopping	Required functionality for simulating non-equilibrium MD

Example

nonadiabatic_processes = .true.
eph_fdm_option = 1
eph_friction_option = 1
eph_random_option = 1
eph_betafile = 'CouplingFile.beta'
eph_Tinfile = 'T_input.fdm'
box_limits = -30.0 30.0 -30.0 30.0 -30.0 30.0    ! in Ang
eph_rho_e = 1.0
eph_C_e = 3.5E-01    ! in eV/K/Ang^3
eph_kappa_e = 0.12   ! in eV/K/Ang/ps
eph_Ti_e = 50.0      ! in K
eph_gsx = 4
eph_gsy = 4
eph_gsz = 4
eph_fdm_steps = 1
eph_md_last_step = 0
eph_md_prev_time = 0.0    ! in fs
eph_E_prev_time = 0.0     ! in eV
eph_freq_Tout = 10
eph_freq_mesh_Tout = 1000
eph_Toutfile = 'T-mesh.out'