Computational chemistry software packages

This appendix is not intended to provide a comprehensive listing of computational chemistry software packages. Some of the software packages listed here are included because they are very widely used. Others are included because they pertained to topics discussed in this book. A few relevant pieces of software were omitted because we were not able to obtain an evaluation copy prior to publication. 

There are many computational chemistry software packages available that enable students to make and study the properties of molecules, by quantum mechanics and molecular mechanics methods. These include Gaussian, HyperChem, Spartan, and Biosym. The first four homework problems assume that the student has one of... 

Such considerations have allowed the development of highly efficient potential energy surface walking algorithms (see, for example, J. Nichols, H. L. Taylor, P. Schmidt, and J. Simons, J. Chem. Phys. 92, 340 (1990) and references therein) designed to trace out streambeds and to locate and characterize, via the local harmonic frequencies, minima and transition states. These algorithms form essential components of most modern ab initio, semi-empirical, and empirical computational chemistry software packages. 

Computational chemistry is essential in a modem physical chemistry course. One approach would be to use laboratory time to have students work through a number of exercises accompanied by elaboration of the concepts in lecture or pre-laboratory discussions. Each of die major computational chemistry software packages come with workbooks or tutorials for learning the software. For example, students can learn by completing exercises in the Spartan tutorials (57). Similar approaches can be taken when using Gaussian (38) and Hyperchem (39) tutorial or exercise collections. 

Hypercube s HyperChem is the best-known computational chemistry software package developed in Canada and marketed worldwide. Hypercube, Inc., the brainchild of Neil Ostlund, was incorporated in February 1985. The company has a headquarters in Waterloo, Ontario, adjacent to the University of Waterloo, but moved most of its operations to Gainesville, Florida, in 1997. 

In this paper the need for an intelligent support of computational chemistry software packages was stressed and the memory-based classification systems suitable for this task recommended. More experiments with selection of relevant features to determine similarity of molecules and methods from the point of view of calculation of molecular properties are needed. Classification systems, such as the FSM, are ready to handle the data, but the task of collecting large amount of data to create a useful system is quite demanding. 

Most of the computational techniques so far discussed are available as commercial software packages, which differ in cost, functionality, efficiency, ease of use, and automation. Some widely used computational chemistry software packages and their Internet addresses are listed in Table 1. 

The properties of these systems are obtained from published experimental data and/or the electronic structure calculations. For crystalline structures, the electronic structure calculations are performed with plane-wave DFT calculations using the software VASP (Vienna Ab initio Simulation Package) with appropriate pseudopotential and exchange-correlation functionals (US-LLDA or PAW-PBE). For molecular systems, the electronic structure calculations are performed using the Gaussian09 computational chemistry software package. Table 7.1 shows the fitting database and predicted values from the COMB potential for Cu. 

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