Scientific input by Per-Olov Löwdin to the Quantum Theory Project

Abstract

Appreciation of Per-Olov Löwdin's scientific accomplishments convinced The University of Florida to engage in the creation of The Quantum Theory Project. This note presents those elements of Löwdin's early oeuvre considered most essential in this respect. These include the treatment of atomic orbital overlap, the formulation of reduced density matrices, the algebraic developments and reformulations of perturbation theory, and the considerations of spin and symmetry projection operators.

Keywords:

• quantum theory
• overlap
• density matrix
• perturbations
• spin