SUBROUTINE VRTP(IDERIV,R,P)
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
      DIMENSION  P(1)
C
C     *****************************************************************
C     *  IF POTENTIAL IS --NOT-- EXPANDED IN ANGULAR FUNCTIONS, I.E., *
C     *    MXSYM.LE.0, THIS ROUTINE MUST SUPPLY THE POTENTIAL AND     *
C     *    ITS 1ST AND 2ND DERIVATIVE (IDERIV=0,1,2, RESPECTIVELY).   *
C     *  EVALUATE POTENTIAL AT ANGLES SPECIFIED IN COMMON /ANGLES/    *
C     *    ITYPE=1: COSANG(1) IS THETA                                *
C     *    ITYPE=2: COSANG(1) IS THETA, COSANG(2) IS VIB COORD        *
C     *    ITYPE=3: COSANG(1),COSANG(2) ARE THETAS, COSANG(3) IS PHI *
C     *  SINCE IHOMO/ICNSYM CANNOT BE DETERMINED BY IOSBGP WITHOUT    *
C     *    ANGULAR TERMS, THEY MAY BE READ IN &POTL OR SET HERE IN    *
C     *    /ANGLES/. VALUES SET HERE OVERRIDE &POTL INPUT.            *
C     *    IF NOT SET, DEFAULT VALUES WILL BE IHOMO=ICNSYM=1          *
C     *  POTENTIAL, RETURNED IN P(1), MUST BE MULTIPLIED BY 'FACTOR'  *
C     *    (SET IN IOSBIN AND PASSED IN /ANGLES/) TO COUNTER LOWEST   *
C     *    ANGULAR FUNCTION (ITYPE DEPENDENT) WHICH MULTIPLIES IT.    *
C     *  INITIALIZATION CALL (IDERIV.LT.0) MAY SET AND/OR USE         *
C     *      RM=R AND EPSIL=P(1)                                      *
C     *****************************************************************
C
      COMMON /ANGLES/COSANG(7),FACTOR,IHOMO,ICNSYM,IHOMO2,ICNSY2
C
      IF (IDERIV.LT.0) THEN
      IHOMO=2
      IHOMO2=1
      WRITE(6,*) ' This is the CO2 - CO PES '
c
      RETURN
      ENDIF
      IF (IDERIV.GT.1) STOP 
C
      P(1)=(POTFUN(R,COSANG(1),COSANG(2),COSANG(3)))*FACTOR

      WRITE(2,101) R,COSANG(1),COSANG(2),COSANG(3),P(1)
 101  format(5f12.4)
      

      RETURN
      END
C---------------------------------------------------

      FUNCTION POTFUN(R,T1,T2,PHI)
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
      COMMON /ANGLES/COSANG(7),FACTOR,IHOMO,ICNSYM,IHOMO2,ICNSY2
      !dimension xi(4)
      character (len=40) :: NAME1
      real*8 :: xi(4),V,pii,th1,th2,phi,ang2boh
      !real*8 r,t1,t2,phi,v,ang2boh
      ang2boh=1.889726d0
      pii = dacos(-1d0)

      NAME1='PES-CO2-CO-2892'
      xi(1)=R/ang2boh
      !xi(1)=r
      xi(2)=COSANG(1)
      xi(3)=COSANG(2)
      xi(4)=COSANG(3)
      !xi(2)=dcos(th1*pii/180.d0)
      !xi(3)=dcos(th2*pii/180.d0)
      xi(4)=xi(4)*(180.d0/pii)
      call PES(xi, V, NAME1, 0, 0)
      POTFUN=V         
      RETURN
      END