MOPAC program

The MOPAC program of CambridgeSoft webpage http //www.camsoft.com... 

Alchemy 2000 (we tested Version 2.05) is a graphic interface for running molecular mechanics and semiempirical calculations. Calculations can be done with the built-in Tripos force field or by calling the MM3 or MOPAC programs, which are included with the package. Alchemy is designed by Tripos and sold by SciVision. 

A valuable review of the MOPAC program and the semi-empirical methods MNDO, MINDO/3, AMI, and PM3. Of particular use are theoretical discussions of these semi-empirical methods and many tables validating the accuracy of the MOPAC program and its associated Hamiltonians. 

Prehminary AMI calculations carried out with the MOPAC program on 18 and related molecules suggest that there are atomic orbital contributions from the heteroatom (e.g., S in 18) to the frontier molecular orbitals. It is conceivable, therefore, that there is negative hyper conjugation involving specific orbitals of S and the P centers in 18. This electronic effect may explain the unusual stabiUty towards oxidation of 18 and other heteroatom functionaUzed primary bisphosphines as described above [51]. 

In addition, detailed geometric and energetic characteristics of the elementary reaction pathways for the addition of water and ammonia to 2-methyl-5(477)-oxazolone have been determined at the AMI level using MOPAC programs. The authors concluded that an A-acetylamino acid or amide are formed through a two-step procedure that involves the formation of the a-hydroxyimine and subsequent tautomerization. 

These immediate and simple findings motivated me to accept Gerrit Schuiirmann s request and to implement COSMO as a new kind of SCRF model in the semi-empirical quantum chemistry package MOPAC [39]. Shortly afterwards, I met Jimmy Stewart, the author of the MOPAC package, in a European Computational Chemistry Workshop in Oxford, where he was available as a supervisor for a entire workshop. I gave a short presentation of my COSMO ideas and he was interested to get COSMO as the first solvation model in MOPAC. Therefore, he introduced me to some extend to the MOPAC program code, and we identified the places where COSMO would have to link in. 

J.J.P. Stewart, MOPAC program package (MOPAC7), QCPE-NO. 455, 1993 J.J.P. Stewart, MOPAC93, Fujitsu Ltd. Tokyo, Japan, 1993. 

MOZYME is a program in the suite of semiempirical programs MOPAC programs reference [58]... 

MOPAC Program Package QCPE No. 455. QCPE, Department of Chemistry, Indiana... 

H. S. Rzepa, M. Y. Yi, M. M. Karelson, and M. C. Zerner,/. Chem. Soc., Perkin Trans. 2, 635 (1991). Geometry Optimisation at the Semiempirical Self-Consistent-Reaction-Field Level Using the AMPAC and MOPAC Programs. 

Several physical-chemical properties of alkanes, polyaromatic hydrocarbons, alkylben-zenes, polychlorobenzenes, polymethylphenols and polychlorophenols were determined using various software packages. The ionization potentials calculated by the MOPAC program was the most suitable property with which to adjust the capacity ratios of polychlorobenzene, polymethylphenol and polychlorophenol isomers . 

Monolayers, self-assembled 997 on gold surfaces 1421 Monte Carlo simulation 107 Montmorillonite catalysis 613-617, 627, 632 MOPAC program 954 Morphine 237... 

The calculation of ab initio wavefunctions for the larger molecules associated with applications such as those discussed later in this paper is computationally demanding. Accordingly, we have also examined these model systems using semi-empirical wavefunctions taken from the well-established MOPAC program [16] such wavefunctions can be obtained very cheaply. Table 3 collects together values of Rab, Sab< Tab and Dab for the model series, evaluated using... 

The hybrid scheme used by us has been described in detail (1). Therefore, only a short summary is given here. The system is divided into a primary (QM) part treated quantum-chemically and the environment treated by a force field (MM part). For the QM part, a semi-empirical calculation is carried out. We have used the MOPAC program (2) for this task and have, consequently, employed all NDDO methods (MNDO, AMI, PM3) in the course of our work. The interactions among atoms of the MM part are described entirely by a classical force field. They are evaluated using die GROMOS87 program (3), and the GROMOS force field or close variations of it were used in our work. 

In 1983 the first MOPAC program was written and contained both the MlNDO/3 and MNDO models. This program allowed geometry optimization, transition state location by use of a reaction coordinate, gradient minimizations, and vibrational frequency calculations. MNDO has been applied with success to the prediction of polarizabilities, hyperpolarizabilities, ESCA, nuclear quadrupole resonance, and numerous other properties. ... 

The MOPAC program (Molecular Orbital PACkag) (26) Is one of the popular quantum mechanical semiempirical methods. The AM1 (Austin Model 1), developed by Michael Dewar (26), is a generalization of the modified neglect of differential diatomic overlap (MNDO) approximation. Often, AM1 is implemented in the MOPAC, and MOPAC(AMt) has been widely used to minimize molecular conformations, to calculate electronic configuration, and to predict such properties as electron distribution and partial charges. 

For the calculation of nonlinear optical properties, Eq. [6] is usually truncated beyond the F term and more complicated expressions result. Bartlett and Purvis advocated this procedure in 1979 and Kurtz et al. implemented it in the MOPAC program. The resulting equations that give NLO properties for the fewest energy calculations using this approach are as follows ... 

The retention time of phenolic compounds in reversed-phase liquid chromatography was predicted via molecular interaction energy values calculated using the MM2 program. The precision of the capacity ratios predicted by this new method was equivalent to a former method in which the retention time was predicted by log P calculated using the MOPAC program. Furthermore, the prediction of capacity ratios of phenolic compounds in reversed-phase... 

The HOMO density, frontier density, superdelocalizability, LUMO density, and ape of all elements were calculated using the MOPAC program after optimizing their structures with molecular mechanics. The ape of the keto and enol forms of phenacylalcohol were constructed using the CAChe system and are shown in Figure 11.10. The electron density of the carbonyl carbon was significantly reduced from the keto to the enol form. 

Table 5 Comparison between elg-FF and conventional PM3 (MOPAC program) calculations for the (hyper)polarizabilities of H-(C2H2)n-H. The size of its starting cluster is N = 20. Here AP = P(N -H 1) - P(N), and elg stands for elongation result and cnv for conventional one...

Over the next decade MNDO parameters were derived for lithium, beryllium, boron, fluorine, aluminum, silicon, phosphorus, sulfur, chlorine,zinc, germanium, bromine, iodine, tin, mercury, and lead. " In 1983 the first MOPAC program was written, containing both the MINDO/3 and MNDO mediods, which allowed various geometric operations, such as geometry optimization, constrained and unconstrained, with and without symmetry, transition state localization by use of a reaction co-... 

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