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Pierre-Francois Loos 2021-03-01 15:01:47 +01:00
parent 5f55c1af4d
commit 7c1304af91
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subroutine UPBE_gga_correlation_energy(nGrid,weight,rho,drho,Ec)
! Compute unrestricted PBE GGA correlation energy
implicit none
include 'parameters.h'
! Input variables
integer,intent(in) :: nGrid
double precision,intent(in) :: weight(nGrid)
double precision,intent(in) :: rho(nGrid,nspin)
double precision,intent(in) :: drho(ncart,nGrid,nspin)
! Local variables
integer :: iG
double precision :: ra,rb,r,rs,z
double precision :: ga,gab,gb,g
double precision :: a,b,c,d
double precision :: gam,beta
double precision :: A_p,a1_p,b1_p,b2_p,b3_p,b4_p
double precision :: A_f,a1_f,b1_f,b2_f,b3_f,b4_f
double precision :: A_a,a1_a,b1_a,b2_a,b3_a,b4_a
double precision :: ec_z,ec_p,ec_f,ec_a
double precision :: fz,d2fz
double precision :: H,kf,ks,t,phi
! Output variables
double precision :: Ec(nsp)
! Parameters for PW92
A_p = 0.031091d0
a1_p = 0.21370d0
b1_p = 7.5957d0
b2_p = 3.5876d0
b3_p = 1.6382d0
b4_p = 0.49294d0
A_f = 0.015545d0
a1_f = 0.20548d0
b1_f = 14.1189d0
b2_f = 6.1977d0
b3_f = 3.3662d0
b4_f = 0.62517d0
A_a = 0.016887d0
a1_a = 0.11125d0
b1_a = 10.357d0
b2_a = 3.6231d0
b3_a = 0.88026d0
b4_a = 0.49671d0
! Parameters PBE
gam = (1d0 - log(2d0))/pi**2
beta = 0.066725d0
! Initialization
Ec(:) = 0d0
do iG=1,nGrid
ra = max(0d0,rho(iG,1))
rb = max(0d0,rho(iG,2))
r = ra + rb
z = (ra - rb)/r
! alpha-alpha contribution
if(ra > threshold) then
rs = (4d0*pi*ra/3d0)**(-1d0/3d0)
ec_f = b1_f*sqrt(rs) + b2_f*rs + b3_f*rs**(3d0/2d0) + b4_f*rs**2
ec_f = -2d0*A_f*(1d0 + a1_f*rs)*log(1d0 + 1d0/(2d0*A_f*ec_f))
ga = drho(1,iG,1)*drho(1,iG,1) + drho(2,iG,1)*drho(2,iG,1) + drho(3,iG,1)*drho(3,iG,1)
kf = (3d0*pi**2*ra)**(1d0/3d0)
ks = sqrt(4d0*kf/pi)
phi = 1d0
t = sqrt(ga)/(2d0*phi*ks*ra)
A = beta/gam/(exp(-ec_f/(gam*phi**3)) - 1d0)
H = gam*phi**3*log(1d0 + beta/gam*t**2*((1d0 + A*t**2)/(1d0 + A*t**2 + A**2*t**4)))
Ec(1) = Ec(1) + weight(iG)*(ec_f + H)*ra
end if
r = ra + rb
! alpha-beta contribution
if(r > threshold) then
rs = (4d0*pi*r/3d0)**(-1d0/3d0)
fz = (1d0 + z)**(4d0/3d0) + (1d0 - z)**(4d0/3d0) - 2d0
fz = fz/(2d0*(2d0**(1d0/3d0) - 1d0))
d2fz = 4d0/(9d0*(2**(1d0/3d0) - 1d0))
ec_p = b1_p*sqrt(rs) + b2_p*rs + b3_p*rs**(3d0/2d0) + b4_p*rs**2
ec_p = -2d0*A_p*(1d0 + a1_p*rs)*log(1d0 + 1d0/(2d0*A_p*ec_p))
ec_f = b1_f*sqrt(rs) + b2_f*rs + b3_f*rs**(3d0/2d0) + b4_f*rs**2
ec_f = -2d0*A_f*(1d0 + a1_f*rs)*log(1d0 + 1d0/(2d0*A_f*ec_f))
ec_a = b1_a*sqrt(rs) + b2_a*rs + b3_a*rs**(3d0/2d0) + b4_a*rs**2
ec_a = +2d0*A_a*(1d0 + a1_a*rs)*log(1d0 + 1d0/(2d0*A_a*ec_a))
ec_z = ec_p + ec_a*fz/d2fz*(1d0-z**4) + (ec_f - ec_p)*fz*z**4
ga = drho(1,iG,1)*drho(1,iG,1) + drho(2,iG,1)*drho(2,iG,1) + drho(3,iG,1)*drho(3,iG,1)
gb = drho(1,iG,2)*drho(1,iG,2) + drho(2,iG,2)*drho(2,iG,2) + drho(3,iG,2)*drho(3,iG,2)
gab = drho(1,iG,1)*drho(1,iG,2) + drho(2,iG,1)*drho(2,iG,2) + drho(3,iG,1)*drho(3,iG,2)
g = ga + 2d0*gab + gb
rs = (4d0*pi*r/3d0)**(-1d0/3d0)
kf = (3d0*pi**2*r)**(1d0/3d0)
ks = sqrt(4d0*kf/pi)
phi = ((1d0 + z)**(2d0/3d0) + (1d0 - z)**(2d0/3d0))/2d0
t = sqrt(g)/(2d0*phi*ks*r)
A = beta/gam/(exp(-ec_p/(gam*phi**3)) - 1d0)
H = gam*phi**3*log(1d0 + beta/gam*t**2*((1d0 + A*t**2)/(1d0 + A*t**2 + A**2*t**4)))
Ec(2) = Ec(2) - weight(iG)*(ec_p + H)*r
end if
! beta-beta contribution
if(rb > threshold) then
rs = (4d0*pi*rb/3d0)**(-1d0/3d0)
ec_f = b1_f*sqrt(rs) + b2_f*rs + b3_f*rs**(3d0/2d0) + b4_f*rs**2
ec_f = -2d0*A_f*(1d0 + a1_f*rs)*log(1d0 + 1d0/(2d0*A_f*ec_f))
gb = drho(1,iG,2)*drho(1,iG,2) + drho(2,iG,2)*drho(2,iG,2) + drho(3,iG,2)*drho(3,iG,2)
kf = (3d0*pi**2*rb)**(1d0/3d0)
ks = sqrt(4d0*kf/pi)
phi = 1d0
t = sqrt(gb)/(2d0*phi*ks*rb)
A = beta/gam/(exp(-ec_f/(gam*phi**3)) - 1d0)
H = gam*phi**3*log(1d0 + beta/gam*t**2*((1d0 + A*t**2)/(1d0 + A*t**2 + A**2*t**4)))
Ec(3) = Ec(3) + weight(iG)*(ec_f + H)*rb
end if
end do
Ec(2) = Ec(2) - Ec(1) - Ec(3)
end subroutine UPBE_gga_correlation_energy

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subroutine UPBE_gga_correlation_potential(nGrid,weight,nBas,AO,dAO,rho,drho,Fc)
! Compute LYP correlation potential
implicit none
include 'parameters.h'
! Input variables
integer,intent(in) :: nGrid
double precision,intent(in) :: weight(nGrid)
integer,intent(in) :: nBas
double precision,intent(in) :: AO(nBas,nGrid)
double precision,intent(in) :: dAO(ncart,nBas,nGrid)
double precision,intent(in) :: rho(nGrid,nspin)
double precision,intent(in) :: drho(ncart,nGrid,nspin)
! Local variables
integer :: mu,nu,iG
double precision :: vAO,gaAO,gbAO
double precision :: ra,rb,r
double precision :: ga,gab,gb,g
double precision :: dfdra,dfdrb
double precision :: dfdga,dfdgab,dfdgb
double precision :: dodra,dodrb,dddra,dddrb
double precision :: a,b,c,d
double precision :: Cf,omega,delta
! Output variables
double precision,intent(out) :: Fc(nBas,nBas,nspin)
! Prameter of the functional
! Compute matrix elements in the AO basis
call UPW92_lda_correlation_potential(nGrid,weight,nBas,AO,rho,Fc)
do mu=1,nBas
do nu=1,nBas
do iG=1,nGrid
ra = max(0d0,rho(iG,1))
rb = max(0d0,rho(iG,2))
r = ra + rb
if(r > threshold) then
ga = drho(1,iG,1)*drho(1,iG,1) + drho(2,iG,1)*drho(2,iG,1) + drho(3,iG,1)*drho(3,iG,1)
gb = drho(1,iG,2)*drho(1,iG,2) + drho(2,iG,2)*drho(2,iG,2) + drho(3,iG,2)*drho(3,iG,2)
gab = drho(1,iG,1)*drho(1,iG,2) + drho(2,iG,1)*drho(2,iG,2) + drho(3,iG,1)*drho(3,iG,2)
g = ga + 2d0*gab + gb
vAO = weight(iG)*AO(mu,iG)*AO(nu,iG)
dfdra = 0d0
dfdrb = 0d0
Fc(mu,nu,1) = Fc(mu,nu,1) + vAO*dfdra
Fc(mu,nu,2) = Fc(mu,nu,2) + vAO*dfdrb
gaAO = drho(1,iG,1)*(dAO(1,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(1,nu,iG)) &
+ drho(2,iG,1)*(dAO(2,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(2,nu,iG)) &
+ drho(3,iG,1)*(dAO(3,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(3,nu,iG))
gaAO = weight(iG)*gaAO
gbAO = drho(1,iG,2)*(dAO(1,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(1,nu,iG)) &
+ drho(2,iG,2)*(dAO(2,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(2,nu,iG)) &
+ drho(3,iG,2)*(dAO(3,mu,iG)*AO(nu,iG) + AO(mu,iG)*dAO(3,nu,iG))
gbAO = weight(iG)*gbAO
dfdga = 0d0
dfdgab = 0d0
dfdgb = 0d0
Fc(mu,nu,1) = Fc(mu,nu,1) + 2d0*gaAO*dfdga + gbAO*dfdgab
Fc(mu,nu,2) = Fc(mu,nu,2) + 2d0*gbAO*dfdgb + gaAO*dfdgab
end if
end do
end do
end do
end subroutine UPBE_gga_correlation_potential