constants.f90

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module constants
 
  use kinds
 
  implicit none
 
  private
 
  public :: array_int
 
  public :: k_b_in_ev, k_b_in_ry, ry_to_ev
 
  !--------------------------------------------------------------------!
  ! KIND to use for arrays storing simulation configurations. int8 is  !
  ! more than enough, as it stores values in the range -128 to 127.    !
  !                                                                    !
  ! C. D. Woodgate,  Bristol                                      2025 !
  !--------------------------------------------------------------------!
 
  integer, parameter :: array_int = int8
 
  !--------------------------------------------------------------------!
  ! Hard-coded physical constants. Mainly for conversion of internal   !
  ! units. (Internally the code works with Rydbergs.)                  !
  !                                                                    !
  ! Currently taken from the CODATA recommended values 2022            !
  ! https://physics.nist.gov/cuu/Constants/index.html                  !
  !                                                                    !
  ! C. D. Woodgate,  Bristol                                      2025 !
  !--------------------------------------------------------------------!
 
  ! 2022 CODATA Value for k_b in eV/K
  real(real64), parameter :: k_b_in_ev &
                             =8.167333262e-5_real64
 
  ! 2022 CODATA Value for k_b in eV/K 
  real(real64), parameter :: k_b_in_ry &
                             =8.167333262e-5_real64/13.605693122990_real64
 
  ! 2022 CODATA value for Rydberg in eV
  real(real64), parameter :: ry_to_ev = 13.605693122_real64
 
end module constants