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Ministerio de EducaciÃ³n y Ciencia (Espanya)  
Feixas GeronÃ¨s, Ferran
Matito i Gras, Eduard Duran i Portas, Miquel SolÃ i Puig, Miquel Silvi, Bernard 

2010  
In this work we present a 2fold approximation for the calculation of the electron localization function (ELF) which avoids the use of the twoparticle density (2PD). 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 2PD. By avoiding the calculation of the 2PD, the present formulation provides the means for routine calculations of the ELF in mediumsize 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. AP20052997. E.M. acknowledges financial support from Marie Curie IntraEuropean Fellowship, Seventh Framework Programme (FP7/20072013), under Grant Agreement No. PIEFGA2008221734 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. CTQ200803077/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 SupercomputaciÃ³ de Catalunya (CESCA) for partial funding of computer time 

application/pdf  
012805  
15499618 (versiÃ³ paper) 15499626 (versiÃ³ electrÃ²nica) 

http://hdl.handle.net/10256/12201  
eng  
American Chemical Society (ACS)  
MEC/PN 20092011/CTQ200803077/BQU ReproducciÃ³ digital del document publicat a: http://dx.doi.org/10.1021/ct1003548 Articles publicats (DQ) 

Â© Journal of Chemical Theory and Computation, 2010, vol. 6, nÃºm. 9, p. 27362742  
Tots els drets reservats  
Orbitals moleculars
Molecular orbitals QuÃmica quÃ ntica Quantum chemistry Electrons  DistribuciÃ³ Electron distribution 

Electron Localization Function at the Correlated Level: A Natural Orbital Formulation  
info:eurepo/semantics/article  
DUGiDocs 