Gaussian Basis Set Order Form

EMSL Gaussian Basis Set Order Form, http //www.emsl.pnl.gov/forms/basisfo-rm.html... 

Commonly used Gaussian basis sets and literature references for them are available on the World Wide Web at the EMSL Gaussian Basis Set Order Form site (www. emsl.pnl.gov 2080/forms/basisform.html) at the Environmental Molecular Sciences Laboratory of the Pacific Northwest Laboratory. 

EXAMPLE Use the Gaussian Basis Set Order Form on the Internet to find the 3-21G basis functions for the oxygen atom. 

In order to form the set of 8 atomic orbitals to be used in the VB calculations, we proceed as follows. We associate to each atom a (8s lp) atomic centered gaussian basis set contracted to [2slp] (Table 1). Each orbital is ex-... 

This is a preliminary exploration of the possibilities for describing processes with potential significance for stereospecificity in chemical reactions. Accurate electronic structure calculations by Ida M. B. Nielsen at the second order Mpller-Plesset perturbation theory level with a (6-3Ig ) Gaussian basis set puts the transform 33.19 milliHartree mEh) below the transition state while the cis-form is... 

The types of (Gaussian) basis sets used in ab initio MO SCF theory have been described elsewhere. It may be helpful to list a few references as examples.The basis set designation in quantiam chemistry appears to be mysterious for non-specialists. However, it frequently has been explained,e.g. recently in a succinct form on current levels of theory. In order to characterize the theoretical level which has been employed for the PES calculation, a double-slash notation is used, introduced by Pople. It characterizes the method and basis set which are used for calculating stationary points of PES ("geometry optimization ) by the information found after the double slashes. The more sophisticated level for subsequent single point calculations of the PES is designated by the information preceding the double slashes. 

Here, hi is the operator for kinetic and electron nuclear attraction energies, and / 2 is the two electron operator (l/r,). Since the Gaussian orbitals in eqn (1-A-l) form a non-orthogonal basis set, the following transformation can be used in order to convert it to an orthogonal basis set ... 

In order to overcome these problems, the core electrons are often excluded from the calculation (frozen-core approximation), and their effect on the valence electrons is parameterized in the form of a pseudo potential based on a relativistic atomic calculation [12]. In connection with GTO basis sets, the most common form of pseudo potential is the effective core potential (ECP) using Gaussian-type radial functions to describe the potential [13-16]. 

Plane wave basis sets of reasonable size (of the order of 100 plane waves per atom) can be used in surface calculations of semiconductors like Si, Ge, GaAs (Hebenstreit et al., 1991) and s-p bonded metals like Al (Needs and Godfrey, 1990). For transition and noble metals the d-elcctrons which participate in the bonding are relatively localized and correspondingly feci a stronger potential than the s- and p-electrons. A plane-wave basis for such systems is unwieldy, and localized Gaussian orbitals of the form ... 

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