mirror of https://github.com/TREX-CoE/qmc-lttc.git
64 lines
1.3 KiB
Fortran
64 lines
1.3 KiB
Fortran
double precision function potential(r)
|
|
implicit none
|
|
double precision, intent(in) :: r(3)
|
|
|
|
double precision :: distance
|
|
|
|
distance = dsqrt( r(1)*r(1) + r(2)*r(2) + r(3)*r(3) )
|
|
|
|
if (distance > 0.d0) then
|
|
potential = -1.d0 / distance
|
|
else
|
|
stop 'potential at r=0.d0 diverges'
|
|
end if
|
|
|
|
end function potential
|
|
|
|
double precision function psi(a, r)
|
|
implicit none
|
|
double precision, intent(in) :: a, r(3)
|
|
|
|
psi = dexp(-a * dsqrt( r(1)*r(1) + r(2)*r(2) + r(3)*r(3) ))
|
|
end function psi
|
|
|
|
double precision function kinetic(a,r)
|
|
implicit none
|
|
double precision, intent(in) :: a, r(3)
|
|
|
|
double precision :: distance
|
|
|
|
distance = dsqrt( r(1)*r(1) + r(2)*r(2) + r(3)*r(3) )
|
|
|
|
if (distance > 0.d0) then
|
|
|
|
kinetic = a * (1.d0 / distance - 0.5d0 * a)
|
|
|
|
else
|
|
stop 'kinetic energy diverges at r=0'
|
|
end if
|
|
|
|
end function kinetic
|
|
|
|
double precision function e_loc(a,r)
|
|
implicit none
|
|
double precision, intent(in) :: a, r(3)
|
|
|
|
double precision, external :: kinetic
|
|
double precision, external :: potential
|
|
|
|
e_loc = kinetic(a,r) + potential(r)
|
|
|
|
end function e_loc
|
|
|
|
subroutine drift(a,r,b)
|
|
implicit none
|
|
double precision, intent(in) :: a, r(3)
|
|
double precision, intent(out) :: b(3)
|
|
|
|
double precision :: ar_inv
|
|
|
|
ar_inv = -a / dsqrt(r(1)*r(1) + r(2)*r(2) + r(3)*r(3))
|
|
b(:) = r(:) * ar_inv
|
|
|
|
end subroutine drift
|