Gaussian 2 calculations

The author acknowledges the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this research. The author is indebted to Prof. W.-K. Li and Dr. S.-W. Chiu for initiating the Gaussian-2 calculations, and to students and postdoctoral fellows K. Norwood, S. Nourbakhsh, C.-L. Liao, C.-X. Liao, C.-W. Hsu, H.-Q. Zhao, Z.-X. Ma, and Y.-S. Cheung in the Ng group at Iowa State University who performed the original work summarized in this review. 

One valid form of the input file is the z-matrix form usually associated with GAUSSIAN calculations... 

A distinction must be made between single-point GAUSSIAN calculations or optimizations and the energy output G2 (0 K). Individual GAUSSIAN calculations produce the energy coming out of the system when all the nuclei and electrons come together to form a molecule, radical, or ion, in this case. 

Carry out a series of calculations comparable to those in Computer Project 10-1 on the hydrogen molecule. Estimate the conelation energy from the GAUSSIAN calculations. 

Although not strictly part of a model chemistry, there is a third component to every Gaussian calculation involving how electron spin is handled whether it is performed using an open shell model or a closed shell model the two options are also referred to as unrestricted and restricted calculations, respectively. For closed shell molecules, having an even number of electrons divided into pairs of opposite spin, a spin restricted model is the default. In other words, closed shell calculations use doubly occupied orbitals, each containing two electrons of opposite spin. 

Multiple Gaussian calculations can be performed from a single input file. See Appendix B (page 294) for details on multi-step jobs. 

Multiple Gaussian calculations may be combined within a single input file. The input for each successive job is separated from that of the preceding job step by a line of the form ... 

Finally, we are performing more rigorous SCF Gaussian calculations on the N,F systems (3). 

Gaussian calculations of S. Rothenberg and H. F. Schaefer III 35), The s/p orbital energies were furnished by Prof. Schaefer. The s/p/d set includes d orbitals on the oxygen atoms as well as the sulfur, while the ARCANA calculation s/pid includes them only for sulfur. 

A few correlated Gaussian calculations have been carried out on systems with more than four particles. On example is the recent work of Komasa et al. [58] on beryllium isoelectronic ions. 

Archival data from GAUSSIAN calculations (atomic coordinates, Hartree-Fcck energies, dipole moments,... 

Fig. 6.17 A screen capture showing the Gaussian calculation setup...

Fig. 7.13 The Gaussian calculation setup screen to select the basis set and the methods for the computation of spectra...

Gaussian calculations on any two-electron diatomic molecule. We will only give some of the results here and refer the reader to the output or program in Appendix B, when necessary. From Appendix A, the overlap of the two basis functions decreases exponentially with the intemuclear distance. At the intemuclear distance R = 1.4632 a.u. its value is S12 = 21 = 0.4508. This overlap is smaller than that in H2 mainly because the He orbital is smaller and more localized than a corresponding H orbital. The overlap matrix is, therefore,... 

Nordlund, G., and A. L. Savolainen. 1983. Application of non-Gaussian Calculation Schemes for Evaluating Atmospheric Transfer of Radionuclides, in IAEA-SR-85/20, vol. 1, International Atomic Energy Agency, pp. 57-65. 

Very fast multipole methods have been developed in order to calculate these electron repulsion integralsl . The near field is determined by analytical Gaussian calculations. The far field is calculated usiug multipole expansions to treat the distant charges and their interactions. The scahng for this approach has been reduced to Fast quadrature... 

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