zeta Function

public elemental function zeta(a, c, qref, qmod)

charge scaling function

Arguments

Type IntentOptional Attributes Name
real(kind=wp), intent(in) :: a
real(kind=wp), intent(in) :: c
real(kind=wp), intent(in) :: qref
real(kind=wp), intent(in) :: qmod

Return Value real(kind=wp)


Source Code

elemental function zeta(a, c, qref, qmod)
   real(wp), intent(in) :: a
   real(wp), intent(in) :: c
   real(wp), intent(in) :: qref
   real(wp), intent(in) :: qmod
   real(wp) :: zeta

   intrinsic :: exp

   if (qmod < 0.0_wp) then
      zeta = exp( a )
   else
      zeta = exp( a * ( 1.0_wp - exp( c * ( 1.0_wp - qref/qmod ) ) ) )
   endif

end function zeta