mirror of
https://github.com/QuantumPackage/qp2.git
synced 2024-11-08 07:03:52 +01:00
62 lines
2.0 KiB
Fortran
62 lines
2.0 KiB
Fortran
double precision function step_function_becke(x)
|
|
implicit none
|
|
BEGIN_DOC
|
|
! Step function of the Becke paper (1988, JCP,88(4))
|
|
END_DOC
|
|
double precision, intent(in) :: x
|
|
double precision :: f_function_becke
|
|
integer :: i,n_max_becke
|
|
|
|
step_function_becke = f_function_becke(x)
|
|
do i = 1, 4
|
|
step_function_becke = f_function_becke(step_function_becke)
|
|
enddo
|
|
step_function_becke = 0.5d0*(1.d0 - step_function_becke)
|
|
end
|
|
|
|
double precision function f_function_becke(x)
|
|
implicit none
|
|
double precision, intent(in) :: x
|
|
f_function_becke = 1.5d0 * x - 0.5d0 * x*x*x
|
|
end
|
|
|
|
! ---
|
|
|
|
double precision function cell_function_becke(r, atom_number)
|
|
|
|
BEGIN_DOC
|
|
! atom_number :: atom on which the cell function of Becke (1988, JCP,88(4))
|
|
! r(1:3) :: x,y,z coordinantes of the current point
|
|
END_DOC
|
|
|
|
implicit none
|
|
double precision, intent(in) :: r(3)
|
|
integer, intent(in) :: atom_number
|
|
integer :: j
|
|
double precision :: mu_ij, nu_ij
|
|
double precision :: distance_i, distance_j, step_function_becke
|
|
|
|
distance_i = (r(1) - nucl_coord_transp(1,atom_number) ) * (r(1) - nucl_coord_transp(1,atom_number))
|
|
distance_i += (r(2) - nucl_coord_transp(2,atom_number) ) * (r(2) - nucl_coord_transp(2,atom_number))
|
|
distance_i += (r(3) - nucl_coord_transp(3,atom_number) ) * (r(3) - nucl_coord_transp(3,atom_number))
|
|
distance_i = dsqrt(distance_i)
|
|
|
|
cell_function_becke = 1.d0
|
|
do j = 1, nucl_num
|
|
if(j==atom_number) cycle
|
|
|
|
distance_j = (r(1) - nucl_coord_transp(1,j) ) * (r(1) - nucl_coord_transp(1,j))
|
|
distance_j += (r(2) - nucl_coord_transp(2,j) ) * (r(2) - nucl_coord_transp(2,j))
|
|
distance_j += (r(3) - nucl_coord_transp(3,j) ) * (r(3) - nucl_coord_transp(3,j))
|
|
distance_j = dsqrt(distance_j)
|
|
|
|
mu_ij = (distance_i - distance_j) * nucl_dist_inv(atom_number,j)
|
|
nu_ij = mu_ij + slater_bragg_type_inter_distance_ua(atom_number,j) * (1.d0 - mu_ij*mu_ij)
|
|
|
|
cell_function_becke *= step_function_becke(nu_ij)
|
|
enddo
|
|
|
|
return
|
|
end
|
|
|