Slide 9 of 17
Jaguar's LMP2 module performs second order Møller-Plesset perturbation theory calculations. This level of theory provides a substantial fraction of the correlation energy and greatly improves transition states, dispersion interactions, hydrogen bonding, conformational energies and other properties.
Jaguar's LMP2 module features a novel implementation of the localized MP2 (LMP2) method proposed by Pulay and Sæbo. In this method, the molecular orbitals are first localized, then correlated through a local virtual space. The size of the local virtual space is independent of the size of the molecule, when combined with the pseudospectral methods, reduces the formal scaling of the method to N3. LMP2 has the additional advantage of greatly reducing the BSSE that is often found in canonical MP2 calculations.
A further reduction in computational efforts can be attained by performing "local local" MP2 calculations, where only some atoms are treated at the LMP2 level, while the rest of the molecule is treated at the HF level. For each atom treated with LMP2, still further efficiency can be gleaned from choosing to freeze the core electrons.