Related Experiment Video
Updated: Jul 12, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
General biorthogonal projected bases as applied to second-order Møller-Plesset perturbation theory
Ville Weijo1, Pekka Manninen, Poul Jørgensen
1Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
Abstract:
With low-order scaling correlated wave function theories in mind, we present second quantization formalism as well as biorthonormalization procedures for general--singular or nonsingular--bases. Of particular interest are the so-called projected atomic orbital bases, which are obtained from a set of atom-centered functions and feature a separation of occupied and virtual spaces. We demonstrate the formalism by deriving and implementing second-order Møller-Plesset perturbation theory in it, and discuss the convergence and preconditioning of the iterative amplitude equations in detail.
Related Concept Videos
Molecular Orbital Theory I
Molecular Orbital Theory II
MO Theory and Covalent Bonding
Hybridization of Atomic Orbitals I
π Molecular Orbitals of 1,3-Butadiene
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
¹H NMR: Complex Splitting
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.

