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QuantumPackage/plugins/local/spher_harm/spher_harm_func.irp.f
2024-07-11 13:57:28 +02:00

165 lines
4.4 KiB
Fortran

subroutine spher_harm_func_r3(r,l,m,re_ylm, im_ylm)
implicit none
integer, intent(in) :: l,m
double precision, intent(in) :: r(3)
double precision, intent(out) :: re_ylm, im_ylm
double precision :: theta, phi,r_abs
call cartesian_to_spherical(r,theta,phi,r_abs)
call spher_harm_func(l,m,theta,phi,re_ylm, im_ylm)
! call spher_harm_func_expl(l,m,theta,phi,re_ylm, im_ylm)
end
subroutine spher_harm_func_m_pos(l,m,theta,phi,re_ylm, im_ylm)
include 'constants.include.F'
implicit none
BEGIN_DOC
! Y_lm(theta,phi) with m >0
!
END_DOC
double precision, intent(in) :: theta, phi
integer, intent(in) :: l,m
double precision, intent(out):: re_ylm,im_ylm
double precision :: prefact,fact,cos_theta,plgndr,p_lm
double precision :: tmp
prefact = dble(2*l+1)*fact(l-m)/(dfour_pi * fact(l+m))
prefact = dsqrt(prefact)
cos_theta = dcos(theta)
p_lm = plgndr(l,m,cos_theta)
tmp = prefact * p_lm
re_ylm = dcos(dble(m)*phi) * tmp
im_ylm = dsin(dble(m)*phi) * tmp
end
subroutine spher_harm_func(l,m,theta,phi,re_ylm, im_ylm)
implicit none
BEGIN_DOC
! Y_lm(theta,phi) with -l<m<+l
!
END_DOC
double precision, intent(in) :: theta, phi
integer, intent(in) :: l,m
double precision, intent(out):: re_ylm,im_ylm
double precision :: re_ylm_pos,im_ylm_pos,tmp
integer :: minus_m
if(abs(m).gt.l)then
print*,'|m| > l in spher_harm_func !! stopping ...'
stop
endif
if(m.ge.0)then
call spher_harm_func_m_pos(l,m,theta,phi,re_ylm_pos, im_ylm_pos)
re_ylm = re_ylm_pos
im_ylm = im_ylm_pos
else
minus_m = -m !> 0
call spher_harm_func_m_pos(l,minus_m,theta,phi,re_ylm_pos, im_ylm_pos)
tmp = (-1)**minus_m
re_ylm = tmp * re_ylm_pos
im_ylm = -tmp * im_ylm_pos ! complex conjugate
endif
end
subroutine cartesian_to_spherical(r,theta,phi,r_abs)
implicit none
double precision, intent(in) :: r(3)
double precision, intent(out):: theta, phi,r_abs
double precision :: r_2,x_2_y_2,tmp
include 'constants.include.F'
x_2_y_2 = r(1)*r(1) + r(2)*r(2)
r_2 = x_2_y_2 + r(3)*r(3)
r_abs = dsqrt(r_2)
if(r_abs.gt.1.d-20)then
theta = dacos(r(3)/r_abs)
else
theta = 0.d0
endif
if(.true.)then
if(dabs(r(1)).gt.0.d0)then
tmp = datan(r(2)/r(1))
! phi = datan2(r(2),r(1))
endif
! From Wikipedia on Spherical Harmonics
if(r(1).gt.0.d0)then
phi = tmp
else if(r(1).lt.0.d0.and.r(2).ge.0.d0)then
phi = tmp + pi
else if(r(1).lt.0.d0.and.r(2).lt.0.d0)then
phi = tmp - pi
else if(r(1)==0.d0.and.r(2).gt.0.d0)then
phi = 0.5d0*pi
else if(r(1)==0.d0.and.r(2).lt.0.d0)then
phi =-0.5d0*pi
else if(r(1)==0.d0.and.r(2)==0.d0)then
phi = 0.d0
endif
if(r(2).lt.0.d0.and.r(1).le.0.d0)then
tmp = pi - dabs(phi)
phi = pi + tmp
else if(r(2).lt.0.d0.and.r(1).gt.0.d0)then
phi = dtwo_pi + phi
endif
endif
if(.false.)then
x_2_y_2 = dsqrt(x_2_y_2)
if(dabs(x_2_y_2).gt.1.d-20.and.dabs(r(2)).gt.1.d-20)then
phi = dabs(r(2))/r(2) * dacos(r(1)/x_2_y_2)
else
phi = 0.d0
endif
endif
end
subroutine spher_harm_func_expl(l,m,theta,phi,re_ylm, im_ylm)
implicit none
BEGIN_DOC
! Y_lm(theta,phi) with -l<m<+l and 0<= l <=2
!
END_DOC
double precision, intent(in) :: theta, phi
integer, intent(in) :: l,m
double precision, intent(out):: re_ylm,im_ylm
double precision :: tmp
include 'constants.include.F'
if(l==0.and.m==0)then
re_ylm = 0.5d0 * inv_sq_pi
im_ylm = 0.d0
else if(l==1.and.m==1)then
tmp = - inv_sq_pi * dsqrt(3.d0/8.d0) * dsin(theta)
re_ylm = tmp * dcos(phi)
im_ylm = tmp * dsin(phi)
else if (l==1.and.m==-1)then
tmp = - inv_sq_pi * dsqrt(3.d0/8.d0) * dsin(theta)
re_ylm = tmp * dcos(phi)
im_ylm = -tmp * dsin(phi)
else if(l==1.and.m==0)then
tmp = inv_sq_pi * dsqrt(3.d0/4.d0) * dcos(theta)
re_ylm = tmp
im_ylm = 0.d0
else if(l==2.and.m==2)then
tmp = 0.25d0 * inv_sq_pi * dsqrt(0.5d0*15.d0) * dsin(theta)*dsin(theta)
re_ylm = tmp * dcos(2.d0*phi)
im_ylm = tmp * dsin(2.d0*phi)
else if(l==2.and.m==-2)then
tmp = 0.25d0 * inv_sq_pi * dsqrt(0.5d0*15.d0) * dsin(theta)*dsin(theta)
re_ylm = tmp * dcos(2.d0*phi)
im_ylm =-tmp * dsin(2.d0*phi)
else if(l==2.and.m==1)then
tmp = - inv_sq_pi * dsqrt(15.d0/8.d0) * dsin(theta) * dcos(theta)
re_ylm = tmp * dcos(phi)
im_ylm = tmp * dsin(phi)
else if(l==2.and.m==-1)then
tmp = - inv_sq_pi * dsqrt(15.d0/8.d0) * dsin(theta) * dcos(theta)
re_ylm = tmp * dcos(phi)
im_ylm =-tmp * dsin(phi)
else if(l==2.and.m==0)then
tmp = dsqrt(5.d0/4.d0) * inv_sq_pi* (1.5d0*dcos(theta)*dcos(theta)-0.5d0)
re_ylm = tmp
im_ylm = 0.d0
endif
end