DUGi

Toward a Unique Definition of the Local Spin

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@300373

In this work, we demonstrate that there is a continuum of different formulations for the decomposition of Ŝ2 that fulfills all physical requirements imposed to date. We introduce a new criterion based upon the behavior of single-electron systems to fix the value of the parameter defining that continuum, and thus we put forward a new general formula applicable for both single-determinant and correlated wave functions. The numerical implementation has been carried out in the three-dimensional physical space for several atomic definitions. A series of representative closed-shell and open-shell systems have been used to illustrate the performance of this new decomposition scheme against other existing approaches. Unlike other decompositions of Ŝ2, the new scheme provides very small local-spin values for genuine diamagnetic molecules treated with correlated wave functions, in conformity with the physical expectations

Financial help has been furnished by the Spanish MICINN Project Nos. CTQ2011-23441/BQU and CTQ2011-23156/BQU and Accion Complementaria del MCI (PCI2006-A7-0631). Financial support from MICINN and the FEDER fund (European Fund for Regional Development) was also provided by grant UNGI08-4E-003. E.R.-C. acknowledges support from the Spanish FPU program (Grant No. AP2008-01231). E.M. acknowledges financial support from the EU under a Marie Curie Career Integration grant (PCI09-GA-2011-294240) and the Beatriu de Pinos program from AGAUR for the postdoctoral grant (BP_B_00236). I.M. acknowledges partial financial support from the Hungarian Scientific Research Fund (grant OTKA 71816)