MOLPRO
MOLPRO is a software package used for accurate ab initio quantum chemistry calculations.^{[1]} It is developed by Peter Knowles at Cardiff University and HansJoachim Werner at Universität Stuttgart in collaboration with other authors.
Developer(s)  H.J. Werner and P. J. Knowles 

Stable release  Molpro version 2019.2

Operating system  Linux, Mac OS 
Type  Computational chemistry 
License  academic 
Website  www 
The emphasis in the program is on highly accurate computations, with extensive treatment of the electron correlation problem through the multireference configuration interaction, coupled cluster and associated methods. Integraldirect local electron correlation methods reduce the increase of the computational cost with molecular size. Accurate ab initio calculations can then be performed for larger molecules. With new explicitly correlated methods the basis set limit can be very closely approached.
HistoryEdit
Molpro was designed and maintained by Wilfried Meyer and Peter Pulay in the late 1960s. At that moment, Pulay developed the first analytical gradient code called HartreeFock (HF),^{[2]}^{[3]}^{[4]} and Meyer researched his PNOCEPA (pseudonatural orbital coupledelectron pair approximation) methods.^{[5]}^{[6]} In 1980, Werner and Meyer developed a new stateaveraged, quadratically convergent (MCSCF) method, which provided geometry optimization for multireference cases.^{[7]} By the same year, the first internally contracted multireference configuration interaction (ICMRCI) program was developed by Werner and Reinsch.^{[8]} About four years later (1984), Werner and Knowles developed on a new generation program called CASSCF (complete active space SCF). This new CASSCF program combined fast orbital optimization algorithms^{[7]} with determinantbased full CI codes,^{[9]} and additional, more general, unitary group configuration interaction (CI) codes. This resulted in the quadratically convergent MCSCF/CASSCF code called MULTI,^{[10]}^{[11]} which allowed modals to be optimized a weighted energy average of several states, and is capable of treating both completely general configuration expansions. In fact, this method is still available today. In addition to these organizational developments, Knowles and Werner started to cooperate on a new, more efficient, ICMRCI method.^{[12]}^{[13]} Extensions for accurate treatments of excited states became possible through a new ICMRCI method.^{[14]} In brief, the present ICMRCI will be described as MRCI. These recently developed MCSCF and MRCI methods resulted in the basis of the modern Molpro. In the following years, a number of new programs were added. Analytic energy gradients can be evaluated with coupledcluster calculations, density functional theory (DFT), as well as many other programs. These structural changes make the code more modular and easier to use and maintain, and also reduces the probability of input error.^{[15]}
See alsoEdit
ReferencesEdit
 ^ Young, David (2001). "Appendix A. A.2.6 MOLPRO". Computational Chemistry. WileyInterscience. p. 338. ISBN 9780471333685.
 ^ Pulay, Peter (1969). "Ab initio calculation of force constants and equilibrium geometries in polyatomic molecules". Molecular Physics. 17 (2): 197–204. Bibcode:1969MolPh..17..197P. doi:10.1080/00268976900100941.
 ^ Pulay, Peter (1970). "Ab initio calculation of force constants and equilibrium geometries in polyatomic molecules. II. Force constants of water". Molecular Physics. 18 (4): 473–480. Bibcode:1970MolPh..18..473P. doi:10.1080/00268977000100541.
 ^ Pulay, Peter (1971). "Ab initio calculation of force constants and equilibrium geometries III. Secondrow hydrides". Molecular Physics. 21 (2): 329–339. Bibcode:1971MolPh..21..329P. doi:10.1080/00268977100101451.
 ^ Meyer, Wilfried (1973). "PNOCI and CEPA studies of electron correlation effects. I. Configuration expansion by means of nonorthogonal orbitals, and application to the ground state and ionized states of methane". Journal of Chemical Physics. 58 (3): 1017–1035. Bibcode:1973JChPh..58.1017M. doi:10.1063/1.1679283.
 ^ Meyer, Wilfried (1974). "PNOCI and CEPA studies of electron correlation effects II. Potential curves and dipole moment functions of the OH radical". Theoretica Chimica Acta. 35 (4): 277–292. doi:10.1007/BF00548478.
 ^ ^{a} ^{b} Werner, HansJoachim; Meyer, Wilfried (1981). "A quadratically convergent MCSCF method for the simultaneous optimization of several states". The Journal of Chemical Physics. 74 (10): 5794. Bibcode:1981JChPh..74.5794W. doi:10.1063/1.440892.
 ^ Werner, HansJoachim; Reinsch, ErnstAlbrecht (1982). "The selfconsistent electron pairs method for multiconfiguration reference state functions". The Journal of Chemical Physics. 76 (6): 3144. Bibcode:1982JChPh..76.3144W. doi:10.1063/1.443357.
 ^ Knowles, P.J.; Handy, N.C. (November 1984). "A new determinantbased full configuration interaction method". Chemical Physics Letters. 111 (4–5): 315–321. Bibcode:1984CPL...111..315K. doi:10.1016/00092614(84)85513X.
 ^ Werner, HansJoachim; Knowles, Peter J. (1985). "A second order multiconfiguration SCF procedure with optimum convergence". The Journal of Chemical Physics. 82 (11): 5053. Bibcode:1985JChPh..82.5053W. doi:10.1063/1.448627.
 ^ Knowles, Peter J.; Werner, HansJoachim (April 1985). "An efficient secondorder MC SCF method for long configuration expansions". Chemical Physics Letters. 115 (3): 259–267. Bibcode:1985CPL...115..259K. doi:10.1016/00092614(85)800257.
 ^ Werner, HansJoachim; Knowles, Peter J. (1988). "An efficient internally contracted multiconfiguration–reference configuration interaction method". The Journal of Chemical Physics. 89 (9): 5803. Bibcode:1988JChPh..89.5803W. doi:10.1063/1.455556.
 ^ Knowles, Peter J.; Werner, HansJoachim (April 1988). "An efficient method for the evaluation of coupling coefficients in configuration interaction calculations". Chemical Physics Letters. 145 (6): 514–522. Bibcode:1988CPL...145..514K. doi:10.1016/00092614(88)874128.
 ^ Knowles, Peter J.; Werner, HansJoachim (1992). "Internally contracted multiconfigurationreference configuration interaction calculations for excited states". Theoretica. 84 (1): 95–103. doi:10.1007/BF01117405.
 ^ Werner, HansJoachim; Knowles, Peter J.; Knizia, Gerald; Manby, Frederick R.; Schutz, Martin (2011). "Molpro: a generalpurposequantum chemistry programpackage". WIREs Computational Molecular Science. 2 (2): 242–253. doi:10.1002/wcms.82.