for orbitals ψ centered at places A, B, C and D. The Gauss Transformation Method has been shown to calculate the integral if the orbitals ψ are expanded in a basis of Gaussian Type Orbitals (GTO’s) [4]; this manuscript basically demonstrates how dealing with the quadratic forms in the exponentials directly also manages to reduce them to the omnipresent Confluent Hypergeometric Functions of the ...

The concept and use of local orbitals are deeply connected to the history Quantum Chemistry. Indeed, most types bonds explained through bonding antibonding orbitals. We describe here main procedures that can be used obtain localized After a brief description underlying formalism, different algorithms compared application simple systems. It is possible, in this way, emphasize advantages inconven...

UNLABELLED Many chemical concepts hinge on the notion of an orbital called the lowest unoccupied molecular orbital, or LUMO. This hypothetical orbital and the much more concrete highest occupied molecular orbital (HOMO) constitute the two "frontier orbitals", which rationalize a great deal of chemistry. A viable LUMO candidate should have a sensible energy value, a realistic shape with amplitud...