gthresh,energy=1.d-8,orbital=1.d-8,grid=1.d-8 symmetry,nosym orient,noorient GEOMETRY={ 1,O1,,0.00000000,0.00000000,0.00000000 2,H1,,0.00000000,0.00000000,1.83606000 3,H2,,1.77604000,0.00000000,-0.4656040 4,O2,,-0.6605540,0.00000000,5.54064000 5,H3,,-1.6582100,-1.4536300,6.05324000 6,H4,,-1.6582100,1.45363000,6.05324000 } basis=avdz !sapt files ca=2101.2 cb=2102.2 !dimer hf edm=energy !monomer A dummy,o2,h3,h4 {hf; save,$ca} ema=energy {sapt;monomerA} !monomer B dummy,o1,h1,h2 {hf; start,atdens; save,$cb} emb=energy {sapt;monomerB} !interaction contributions {sapt,SAPT_LEVEL=3;intermol,ca=$ca,cb=$cb,icpks=1} !HF supermolecular interaction energy and delta(HF) contribution eint_hf=(edm-ema-emb)*1000 mH delta_hf=eint_hf-e1pol-e1ex-e2ind-e2exind !add E2disp + E2exch-disp to HF interaction energy eint_sapt=eint_hf+e2disp+e2exdisp