Search results for "Multi-configurational self-consistent field"

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Multi-scale multireference configuration interaction calculations for large systems using localized orbitals: Partition in zones

2012

A new multireference configuration interaction method using localised orbitals is proposed, in which a molecular system is divided into regions of unequal importance. The advantage of dealing with local orbitals, i.e., the possibility to neglect long range interaction is enhanced. Indeed, while in the zone of the molecule where the important phenomena occur, the interaction cut off may be as small as necessary to get relevant results, in the most part of the system it can be taken rather large, so that results of good quality may be obtained at a lower cost. The method is tested on several systems. In one of them, the definition of the various regions is not based on topological considerati…

010304 chemical physicsChemistryGeneral Physics and AstronomyMultireference configuration interactionMolecular orbital theory010402 general chemistry01 natural sciences0104 chemical sciencesLinear combination of atomic orbitalsMulti-configurational self-consistent field0103 physical sciencesMolecular orbitalComplete active spaceStatistical physicsPhysical and Theoretical ChemistryAtomic physicsBasis setNatural bond orbital
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Linear scaling exchange gradients for Hartree–Fock and hybrid density functional theory

2000

Abstract A new method is introduced which allows to form the exchange part of self-consistent field energy gradients in a way which scales linearly with molecular size for molecules with a non-vanishing HOMO–LUMO gap. This is not only important for Hartree–Fock but as well for the popular hybrid density functional theory methods. The method preserves the optimized integral-driven structure of conventional direct methods. Efficiency and scaling behavior of the new method are illustrated for DNA fragments.

ChemistryMulti-configurational self-consistent fieldQuantum mechanicsHartree–Fock methodRestricted open-shell Hartree–FockGeneral Physics and AstronomyUnrestricted Hartree–FockDensity functional theoryStatistical physicsPhysical and Theoretical ChemistryScalingPost-Hartree–FockHybrid functionalChemical Physics Letters
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