AMPAC program

One very popular technique is an adaptation of the Born model for orbital-based calculations by Cramer and Truhlar, et. al. Their solvation methods (denoted SMI, SM2, and so on) are designed for use with the semiempirical and ah initio methods. Some of the most recent of these methods have a few parameters that can be adjusted by the user in order to customize the method for a specific solvent. Such methods are designed to predict ACsoiv and the geometry in solution. They have been included in a number of popular software packages including the AMSOL program, which is a derivative of AMPAC created by Cramer and Truhlar. 

AMPAC (we tested Version 6.51) is a semiempirical program. It comes with a graphic user interface (we tested Version 6.0). The documentation included with the package is well written. 

AMPAC can also be run from a shell or queue system using an ASCII input file. The input file format is easy to use. It consists of a molecular structure defined either with Cartesian coordinates or a Z-matrix and keywords for the type of calculation. The program has a very versatile set of options for including molecular geometry and symmetry constraints. 

GaussView (we used Version 2.08) is a graphic interface for use with the Gaussian ah initio program. It can be used to build molecules, set up the options in the input hie, run a calculation, and display results. GaussView uses the molecule builder that was written by SemiChem, but has screens for setting up calculations that are different from those in the AMPAC GUI sold by SemiChem. 

Semi-empirical methods, such as AMI, MINDO/3 and PM3, implemented in programs like MOPAC, AMPAC, HyperChem, and Gaussian, use parameters derived from experimental data to simplify the computation. They solve an approximate form of the Schrodinger equation that depends on having appropriate parameters available for the type of chemical system under investigation. Different semi-emipirical methods are largely characterized by their differing parameter sets. 

Semi-empirical methods are characterized by their use of parameters derived from experimental data in order to simplify the approximation to the Schrbdinger equation. As such, they are relatively inexpensive and can be practically applied to very, very large molecules. There are a variety of semi-empirical methods. Among the best known are AMI, PM3 and MNDO. Gaussian includes a variety of semi-empirical models, and they are also the central focus or present in many other programs including AMPAC, MOPAC, HyperChem and Spartan. 

SemiChem products are available at http //www.semichem.com/prods.html. AMPAC , available as a stand-alone product with Windows-based and work-station-level interfaces, is a semiempirical quantum mechanical program featuring SAMI, AMI, MNDO, MNDO/d, PM3, MNDO/C, and MINDO/3 semiempirical... 

The current status of the semiempirical methods pioneered by Michael J. S. Dewar is given. These methods are made available to non—theoreticians through the programs MOP AC and AMPAC. Some capabilities of MOPAC and the form of the data input to the program are outlined. 

AMP AC is a semiempirical suite of programs. It can be leased from Semichem, Inc., http // www.semichem.com/default.php, 12456 W, 62nd Terrace, Suite D, Shawnee, KS 66216, USA. As of mid-2009, the latest version of AMP AC was AMPAC 9. The name means Austin method package cf. AMI... 

Outputs molecule structure files in formats readable by MM2, MM3, MOPAC, AMPAC, MacroModel, and other programs. XDRAW for displaying input and output of MOPAC. BOLTZMANN for conformer populations. VAX, UNIX, and DOS versions. 

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. 

Figure 12 Number of publications per year in the CJACS file mentioning semiem-pirical MO programs MOPAC, AMPAC, AMSOL, or ZINDO. The search queries for each curve were (1) mopac, (2) ampac, (3) amsol, and (4) zindo.

Austin Model 1 Ampac version available through the Department of Chemistry, Indiana University, Bloomington, Indiana, 47405, QCPE Program 506. 

Many popular semiempirical methods are based on the original MNDO method. The most prominent of these are Austin Model 1 (AMI) by Dewar et al. [73] and Parametric Method 3 (PM3) by Stewart [74], These three methods represent the semiempirical standard for the calculation of organic molecules and are included in popular program packages such as Gaussian [78], CERIUS [79], SPARTAN [80], MOP AC [81], and AMPAC [82], Recently, AM 1 and PM3 have also been extended for the treatment of transition metal compounds [75-77], In principle, they only differ in the parameterization and in the empirical function fAB [Eq. (42)]. 

The SINDOl program is less generally available than either AMPAC, MOPAC, or ZINDO, but a considerable amount of literature using this method is beginning to appear. The model, as described above, has been parameterized on experimental geometries, binding energies, dipole moments, and ionization potentials. Many comparisons between SINDOl and MINDO/3 and MNDO appear, and we reproduce some of these comparisons in Tables 5 and 6. 

If the reaction path is not obvious, then the most general techniques require information about the second derivatives. There exist, however, several often successful techniques that do not require this. The MOPAC and AMPAC series of programs utilize, for example, the saddlepoint technique, which attempts to approach the transition state from the reactant and product geometry simultaneously. The ZINDO set of models can utilize a combination of augmented Hessian and analytic geometry techniques. This is a very effective method, but unfortunately the augmented Hessian method does require approximate second derivatives and is somewhat time consuming. 

Extensive catalog of programs for quantum mechanics, molecular mechanics, and molecular graphics, including DRAW (a graphical complement to MOPAC), AMPAC, MM2, CNINDO/D, FORTICON8 (Extended Hiickel), MNDO, HAM/3, POLYATOM, MOLVIEW, NAMOD, etc. PC and Mac-II. 

---