Relativistic Internally Contracted Multireference Electron Correlation Methods

Reduced Scaling Electron Correlation Methods

We give a detailed description of recent developments in reduced scaling ab initio methods for treating electron correlation in atoms and molecules. Since configuration interaction (CI) is the simplest electron correlation method, it is introduced first and used as a context to describe the familiar local correlation and pseudospectral approximations. The article then goes on to discuss the app...

Basis set limit electronic excitation energies, ionization potentials, and electron affinities for the 3d transition metal atoms: Coupled cluster and multireference methods.

Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s(2)3d(n-2)-4s(1)d(n-1) electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration inter...

A transformed framework for multireference dynamic correlation

Multireference correlation remains a driving force for the development of new quantum chemical methods. There are now many methods to describe the correlation in the active spaces with up to 50 orbitals that produce a multireference wavefunction that is formally the sum of many determinants. The remaining challenge is to efficiently describe dynamic correlation outside of the active space. Dyna...

Economical treatments of relativistic effects and electron correlation in WH6

Relativistic correlation

Fundamental breakthroughs have recently been achieved in relativistic quantum chemistry based on the no-pair Dirac-Coulomb-Breit Hamiltonian (for a recent review see Ref. [1]). However, there still exist two issues that require great attention, i.e., how to go beyond the nopair approximation so as to account for the correlation contributions of negative energy states and how to do relativistic ...