!----------------------------------------------------------------------
SUBROUTINE potaph (rho, theta, xchi, pot)
USE Numeric_Kinds_Module
USE FileUnits_Module
USE Masses_Module
USE Save_Module
USE Narran_Module
!            P U R P O S E   O F    S U B R O U T I N E
! This routine calculates interparticle distances in Bohr and THEN
! calls surface to determine the interaction potential in Hartree's.
!            I N P U T    A R G U M E N T S
!      rho    hyperradius in Bohr.          (0 <  rho  < infinity)
!      theta  hyperangle theta in radians.  (0 < theta < pi/2)
!      xchi   hyperangle chi in radians.    (0 <  chi  < 2pi)
!            O U T P U T    A R G U M E N T S
!      pot    potential energy V(rho,theta,chi) in Hartree atomic units.
! <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
IMPLICIT NONE
!            I N T E G E R S

INTEGER :: k
!            R E A L S


REAL (dp) :: pot, rho, theta, xchi, sbig (narran)
!-----------------------------------------------------------------------
!  Calculate the interpartical distances and store them in the arrary r.
!-----------------------------------------------------------------------

chi3 (1) = xchi
chi3 (2) = chi3 (1) - chij (2, 1)

chi3 (3) = chi3 (1) - chij (3, 1)

 DO k = 1, narran
   s (k) = rho * sqrt (0.5d0 - 0.5d0 * sin (theta) * cos (2.d0 * chi3 (k) ) )
   sbig (k) = rho * sqrt (0.5d0 + 0.5d0 * sin (theta) * cos (2.d0  * chi3 (k) ) )

   r (k) = d (k) * s (k)

 ENDDO
!-----------------------------------------------------------------------
! This CALL returns the interaction potential in Hartree atomic units.
!-----------------------------------------------------------------------

CALL surface (pot, r)

RETURN
END SUBROUTINE potaph