1
0
mirror of https://github.com/TREX-CoE/qmc-lttc.git synced 2024-11-02 04:04:06 +01:00
qmc-lttc/hydrogen.f90

46 lines
1.3 KiB
Fortran
Raw Normal View History

2021-01-03 18:45:58 +01:00
double precision function potential(r)
implicit none
double precision, intent(in) :: r(3)
2021-01-26 00:22:37 +01:00
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 / dsqrt( r(1)*r(1) + r(2)*r(2) + r(3)*r(3) )
else
stop 'potential at r=0.d0 diverges'
end if
2021-01-03 18:45:58 +01:00
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)
2021-01-26 00:22:37 +01:00
double precision :: distance
distance = dsqrt( r(1)*r(1) + r(2)*r(2) + r(3)*r(3) )
if (distance > 0.d0) then
kinetic = -0.5d0 * (a*a - (2.d0*a) / distance)
else
stop 'kinetic energy diverges at r=0'
end if
2021-01-03 18:45:58 +01:00
end function kinetic
double precision function e_loc(a,r)
implicit none
double precision, intent(in) :: a, r(3)
double precision, external :: kinetic, potential
e_loc = kinetic(a,r) + potential(r)
end function e_loc
2021-01-12 01:01:52 +01:00
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