C RICOQ0    SOURCE    CHAT      05/01/13    02:56:14     5004
      SUBROUTINE RICOQ0(RIG,X13,X23,Y13,Y23,FAC)
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8(A-H,O-Z)
      DIMENSION RIG(18,18),VEC(18)
*
      S=(X13*Y23-X23*Y13)*2.D0
      FAC4=FAC*4.D0
      DO 100 I=1,18
100   VEC(I)=0.
      VEC(1)=-X23/S
      VEC(2)=-Y23/S
      VEC(7)=X13/S
      VEC(8)=Y13/S
      VEC(13)=(X23-X13)/S
      VEC(14)=(Y23-Y13)/S
      DO 102 I=1,3
      I6=6*I
      VEC(6) =0.D0
      VEC(12)=0.D0
      VEC(18)=0.D0
      VEC(I6)=1.D0
      DO 103 J=1,18
      DO 103 K=1,18
      RIG(J,K)=RIG(J,K)+VEC(J)*VEC(K)*FAC4
 103  CONTINUE
 102  CONTINUE
*
      RETURN
      END