MOLPRO program system

Parameters of energy-consistent ab initio pseudopotentials and corresponding valence basis sets are available for almost all elements of the periodic table [93,94,117,190-192,194-201]. A compilation of parameters for the use within the MOLPRO program system also exists on the internet under the address http //www.theochem.uni-stuttgart.de. Special care has to be taken when spin-orbit coupling is included in calculations with small-core PPs some SO operators are constructed (similar to the large-core case) for a fully variational two-component treatment, whereas in some cases effective valence SO operators are defined. The latter have to be applied in SO-CI calculations for the valence electrons, in which the semi-core shells (outside the PP core) are frozen in their scalar-relativistic form. 

The CCSD approach has been in recent years efficiently implemented in several program systems (ACES II, CADPAC, DALTON, GAUSSIAN, MOLCAS, MOLPRO, PSI, TITAN). In particular, vectorization, exploitation of Abelian point-group symmetry, and (partial) AO-based algorithms have been used to accomplish this task. Calculations for molecules with up to ten nonhydrogen atoms... 

Intended for high-level correlated ab initio calculations (multiconfiguration SCF, multireference Cl, and CC). The emphasis is on highly accurate computations. .. accurate ab initio calculations can be performed for much larger molecules than with most other programs. MOLPRO has been ran on a variety of machines with UNIX-type operating systems. 

VSCF, CC-VSCF and related algorithms are incorporated in the ab initio code packages gamess [3] and molpro [5]. In both cases, developers of the systems made important improvements to the codes (Dr. M.W. Schmidt for gamess. Dr. G. Rahut and Prof. H.-J. Werner for molpro). There have been numerous applications of the VSCF codes through use of the gamess suite of programs. 

The CBS-QCI/APNO scheme involves QCISD(T)/6-3114"fG(2df,p) calculations, which are fairly time-consuming with Gaussian 94 but (if the system has any symmetry at all) can be carried out quite rapidly using a fast coupled cluster program such as that in MOLPRO 96. It also approximately includes core-correlation. The results are quite respectable the mean absolute error for our reference set is 0.45 kcal mol on a par with 3PC/cc-pVQZ (0.45 kcal mol ) or 3PC4-core/cc-pVQZ (0.48 kcal mol ). For those who have fast coupled cluster codes available, however, and require that kind of accuracy, 3PC/aug -cc-pVQZ (0.32 kcal mol ) or even 3PC4-core/aug -cc-pVQZ (0.23 kcal mol ) might be more attractive. 

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