DUGi

Electron Localization Function at the Correlated Level: A Natural Orbital Formulation

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@297518

In this work we present a 2-fold approximation for the calculation of the electron localization function (ELF) which avoids the use of the two-particle density (2-PD). The first approximation is used for the calculation of the ELF itself and the second one is used to approximate pair populations integrated in the ELF basins. Both approximations only need the natural orbitals and their occupancies, which are available for most methods used in electronic structure calculations. In this way, methods such as CCSD and MP2 can be used for the calculation of the ELF despite the lack of a pertinent definition of the 2-PD. By avoiding the calculation of the 2-PD, the present formulation provides the means for routine calculations of the ELF in medium-size molecules with correlated methods. The performance of this approximation is shown in a number of examples

F.F. thanks the MICINN for a doctoral fellowship, No. AP2005-2997. E.M. acknowledges financial support from Marie Curie IntraEuropean Fellowship, Seventh Framework Programme (FP7/2007-2013), under Grant Agreement No. PIEF-GA-2008-221734 and from the Polish Ministery of Science and Higher Education (Project No. N N204 215634). M.S. and F.F. are grateful for financial help furnished by the Spanish MICINN Project No. CTQ2008-03077/BQU and by the Catalan DIUE through Project No. 2009SGR637. Support for the research of M. S. was received through the ICREA Academia prize for excellence in research funded by the DIUE of the Generalitat de Catalunya. We thank the Centre de Supercomputació de Catalunya (CESCA) for partial funding of computer time

American Chemical Society (ACS)