15 Integral-direct calculations

With the exception of perturbative triples corrections, all methods implemented in MOLPRO can be performed
in integral-direct mode, i.e., without storage of the two-electron integrals on disk. Naturally, this takes longer
than conventional calculations, since the integrals are recomputed whenever needed. The integral-direct mode is
activated by giving the `gdirect` directive before the first energy calculation, e.g.,

***,formaldehyde print,basis,orbitals !this is optional: print the basis set and the !occupied orbitals angstrom geometry={ !define the nuclear coordinates C O , C , rco H1 , C , rch , O , hco H2 , C , rch , O , hco , H1 , 180 } rco=1.182 Ang rch=1.102 Ang hco=122.1789 Degree gdirect !integral-direct calculation basis=vdz !Select basis set hf !Perform HF calculation mp2 !Perform MP2 calculation

molpro@molpro.net 2019-03-22