thermostats_m.F90

module thermostats_m
    use, intrinsic :: iso_fortran_env, only: dp => real64, i64 => int64
    use            :: math_utils_m,    only: r8_normal_ab
    use            :: interface_m,     only: databloc_params_t
    implicit none

    public :: andersen_thermostat

contains

subroutine andersen_thermostat(vel, parambox)
    implicit none
    ! In/Out variables
    real(kind=DP), dimension(:,:), intent(out) :: vel
    type(databloc_params_t), intent(in)        :: parambox
    ! Internal variables
    integer(kind=I64) :: j_part, i_coord
    real(kind=DP)     :: rand_numb, sig

    sig = sqrt(parambox%ref_temp)

    do j_part = 1, size(vel, dim=2)
        call random_number( harvest = rand_numb )
        if (rand_numb < parambox%andersen_nu) then
            do i_coord = 1, 3
                vel(i_coord, j_part) = r8_normal_ab(a=0.0_DP, b=sig)
            end do 
        end if
    end do 
end subroutine andersen_thermostat

end module thermostats_m