***,HF dimer MP2/CP optimization with relaxed monomers basis=avtz gthresh,energy=1.d-8 ! INITIAL VALUES OF GEOMETRY VARIABLES RFF= 5.3 R1= 1.76 R2 = 1.75 THETA1 = 7.0 THETA2 = 111 symmetry,x orient,noorient geometry={ f1 f2 f1 rff h1 f1 r1 f2 theta1 h2 f2 r2 f1 theta2 h1 180.} label: text, CALCULATION AT LARGE SEPARATION rff_save=rff !save current rff distance rff=1000 !dimer calculation at large separation text, HF1 dummy,f2,h2; !second hf is now dummy {hf;accu,16} !scf for first monomer mp2; !mp2 for first monomer ehf1inf=energy !save mp2 energy in variable forces; !compute mp2 gradient for first monomer text, HF2 dummy,f1,h1; !first hf is now dummy {hf;accu,16} !scf for second monomer mp2; !mp2 for second monomer ehf2inf=energy !save mp2 energy in variable forces; !compute mp2 gradient for second monomer add,1 !add to previous gradient einf=ehf1inf+ehf2inf !total energy of unrelaxed momomers rff=rff_save !reset HF - HF distance to current value text, CP calculation for HF1 MONOMER dummy,f2,h2; !second hf is now dummy {hf;accu,16} !scf for first monomer mp2; !mp2 for first monomer ehf1=energy !save mp2 energy in variable forces; !compute mp2 gradient for first monomer add,-1 !subtract from previous gradient text, CP calculation for HF2 MONOMER dummy,f1,h1; !first hf is now dummy {hf;accu,16} !scf for second monomer mp2; !mp2 for second monomer ehf2=energy !save mp2 energy in variable forces; !compute mp2 gradient for first monomer add,-1 !subtract from previous gradient text, DIMER CALCULATION dummy !reset dummies {hf;accu,16} !scf for dimer mp2; !mp2 for dimer edimer=energy !save mp2 energy in variable forces; !compute mp2 gradient for dimer add,1 !add to previous gradient optg,gradient=1.d-4,startcmd=label: !find next energy text, compute optimized monomer energy rhf=r1 geometry={h1 F1,H1,rhf} {hf;accu,16} !scf for relaxed monomer mp2; !mp2 for relaxed monomer ehf=energy !save mp2 energy in variable optg !optimize HF structure text,optimized geometry parameters show,r1,r2,rhf,rff,theta1,theta2 text,computed interaction energies decpc=(einf-ehf1-ehf2)*tocm !counter poise correction de=(edimer-ehf1-ehf2)*tocm !CPC corrected interaction energy relative to unrelaxed monomers erelax=(2*ehf-einf)*tocm !relaxation energy derel=de-erelax !CPC corrected interaction energy relative to relaxed monomoers