Gaussian program FIELD

Since the development of the Onsager model, there have been a number of elaborations on the model [4,5]. For example, the spherical cavity has been replaced by molecularly-shaped cavities. The state of the art within the field of solvent effects described by continuum solvent models is now implemented in, e.g., the Gaussian program package. 

In our ongoing study of energetic systems, we use primarily an ab initio self-consistent-field (SCT) molecular orbital approach utilizing the GAUSSIAN programs [18-20] to compute wave functions and specific properties of interest. In this section we will discuss geometry optimizations and the importance of understanding basis set effects in computational work. 

A survey of computed properties of secondary nitramines has been presented and discussed in light of both their fundamental interest and also their possible relation to impact/shock sensitivity and thermal stability. Our overall computational approach has used the sh. initio self-consistent-field molecular orbital GAUSSIAN programs to calculate optimized structures (primarily at the 3-21G level), molecular energies and STO-5G electrostatic potentials for molecules of interest. 

Further, it is understood that each matrix element consists of the components originating in the pure QM, the est and the vdW contribution. The est components are conveniently computed by the quantum chemical calculation package. For instance, in GAUSSIAN program [25], several approximate methods of electronic state calculations are available, e.g., the Hartree-Fock (HF), second-order Moller-Plesset perturbation theory (MP2), conhguration interaction field (CIS), complete active space self-consistent field (CASSCF) method, and the density functional theory (DFT) methods. On the other hand, since the vdW components are expressed as such analytical functions of the mw Cartesian coordinate variables involved in the same atom (A = B) as follows. 

Similar problems can be set for CH2FCH2F, NHF=NHF, and many related species.] 6.3. [For this problem, it is assumed that your ESS program can perform finite-field calculations for chosen electric fields along chosen directions. In the Gaussian program, use the NOSYMM keyword to obtain the desired molecular orientation with respect to Cartesian x-y axes.]... 

The following are programs created specifically for force field based simulations. There are also molecular mechanics programs bundled with the Spartan, Gaussian, and Hyperchem products discussed previously in this appendix. 

The field of quantum chemistry has seen tremendous development over the last thirty years. Thanks to high-accuracy models such as coupled-cluster theory and standardized, widely available program packages such as Gaussian 98, what was once merely an esoteric tool of a few specialists has evolved into an indispensable source of knowledge for both the prediction and the interpretation of chemical phenomena. With the development of reduced scaling algorithms for coupled cluster... 

In the mid-nineties more highly correlated methods such as CCSD and QCISD became available through distribution of the ACES and Gaussian 94 programs. Geometry optimization with these more cpu intensive programs was restricted for the most part to six heavy atoms. About this time multiconfigurational self-consistent-field (MCSCF) or... 

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