1 SUBROUTINE GOVER(NI,NJ,XI,XJ,R,SG) 2************************************************************************ 3* * 4* GOVER CALCULATES THE OVERLAP INTEGRALS USING A GAUSSIAN EXPANSION * 5* STO-6G BY R.F. STEWART, J. CHEM. PHYS., 52 431-438, 1970 * 6* * 7* ON INPUT NI = ATOMIC NUMBER OF FIRST ATOM * 8* NJ = ATOMIC NUMBER OF SECOND ATOM * 9* R = INTERATOMIC DISTANCE IN ANGSTROMS * 10* ON EXIT S = 9X9 ARRAY OF OVERLAPS, IN ORDER S,PX,PY, * 11* PZ * 12* * 13************************************************************************ 14 IMPLICIT DOUBLE PRECISION (A-H,O-Z) 15 INCLUDE 'SIZES' 16 COMMON /NATYPE/ NZTYPE(107), MTYPE(30),LTYPE 17 COMMON /TEMP/ C(60,6), Z(60,6) 18 COMMON /NATORB/ NATORB(107) 19 DIMENSION S(6,6), XI(3),XJ(3), SG(9,9) 20 SAVE NGAUSS 21 DATA NGAUSS/6/ 22C 23C FIND START AND END OF GAUSSIAN 24C 25 IFA=NZTYPE(NI)*4-3 26 IF(C(IFA+1,1).NE.0.D0)THEN 27 ILA=IFA+3 28 ELSE 29 ILA=IFA 30 ENDIF 31 IFB=NZTYPE(NJ)*4-3 32 IF(C(IFB+1,1).NE.0.D0)THEN 33 ILB=IFB+3 34 ELSE 35 ILB=IFB 36 ENDIF 37C 38C CONVERT R INTO AU 39C 40 R=R/0.529167D0 41 R = R**2 42 KA=0 43 DO 80 I=IFA,ILA 44 KA=KA+1 45 NAT=KA-1 46 KB=0 47 DO 80 J=IFB,ILB 48 KB=KB+1 49 NBT=KB-1 50C 51C DECIDE IS IT AN S-S, S-P, P-S, OR P-P OVERLAP 52C 53 IF(NAT.GT.0.AND.NBT.GT.0) THEN 54C P-P 55 IS=4 56 TOMB=(XI(NAT)-XJ(NAT))*(XI(NBT) 57 1-XJ(NBT))*3.5711928576D0 58 ELSEIF(NAT.GT.0) THEN 59C P-S 60 IS=3 61 TOMB=(XI(NAT)-XJ(NAT))*1.88976D0 62 ELSEIF(NBT.GT.0) THEN 63C S-P 64 IS=2 65 TOMB=(XI(NBT)-XJ(NBT))*1.88976D0 66 ELSE 67C S-S 68 IS=1 69 ENDIF 70 DO 60 K=1,NGAUSS 71 DO 60 L=1,NGAUSS 72 S(K,L)=0.0D0 73 AMB=Z(I,K)+Z(J,L) 74 APB=Z(I,K)*Z(J,L) 75 ADB=APB/AMB 76C 77C CHECK OF OVERLAP IS NON-ZERO BEFORE STARTING 78C 79 IF((ADB*R).LT.90.D0) THEN 80 ABN=1.0D0 81 GO TO(50,10,20,30),IS 82 10 ABN=2.D0*TOMB*Z(I,K)*SQRT(Z(J,L))/AMB 83 GO TO 50 84 20 ABN=-2.D0*TOMB*Z(J,L)*SQRT(Z(I,K))/AMB 85 GO TO 50 86 30 ABN=-ADB*TOMB 87 IF(NAT.EQ.NBT) ABN=ABN+0.5D0 88 40 ABN=4.0D0*ABN*SQRT(APB)/AMB 89 50 S(K,L)=SQRT((2.D0*SQRT(APB)/AMB)**3)*EXP(-ADB*R)* 90 . ABN 91 ENDIF 92 60 CONTINUE 93 SG(KA,KB)=0.0D0 94 DO 70 K=1,NGAUSS 95 DO 70 L=1,NGAUSS 96 70 SG(KA,KB)=SG(KA,KB)+S(K,L)*C(I,K)*C(J,L) 97 80 CONTINUE 98 RETURN 99 END 100