Glossary of terms used in theoretical
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Gaussian type orbital (GTO)
- An exponential function centered on an atom, the general expression
for which is given by
c (a, r)
where i, j, k are positive integers or zero
and a is the orbital exponent. Orbitals of
s, p, and d type result when i + j + k = 0,
1, 2 respectively. Linear combinations of primitive gaussians are used
to form the actual basis functions
that are called contracted gaussians.The great convenience of GTOs
lies in the fact that evaluation of the molecular integrals needed in
quantum mechanical methods of calculation is performed much
more efficiently as compared with Slater
type atomic orbitals.
Generalized Valence Bond (GVB)
method - A multiconfigurational method that uses a limited set
of valence bond configurations in the conventional multiconfiguration
Ghost orbitals - see Counterpoise
Gradient norm - see Energy
Graph - A representation consisting of points
(vertices) connected by lines (edges). A graph is a topological,
but not a geometric object.
Graph automorphism group -
The set of all permutations of graph vertices
in which adjacent vertices remain adjacent.
Ground state - The lowest
energy state of a chemical entity.