Multicomponent density functional theory study of the interplay between electronelectron and electronproton correlation
Abstract
The interplay between electronelectron and electronproton correlation is investigated within the framework of the nuclearelectronic orbital density functional theory (NEODFT) approach, which treats electrons and select protons quantum mechanically on the same level. Recently two electronproton correlation functionals were developed from the electronproton pair densities obtained from explicitly correlated wavefunctions. In these previous derivations, the kinetic energy contribution arising from electronproton correlation was neglected. In this paper, an electronproton correlation functional that includes this kinetic energy contribution is derived using the adiabatic connection formula in multicomponent DFT. The performance of the NEODFT approach using all three electronproton correlation functionals in conjunction with three wellestablished electronic exchangecorrelation functionals is assessed. NEODFT calculations with these electronproton correlation functionals capture the increase in the hydrogen vibrational stretching frequencies arising from the inclusion of electronelectron correlation in model systems. Electronproton and electronelectron correlation are found to be uncoupled and predominantly additive effects to the total energy for the model systems studied. Thus, electronproton correlation functionals and electronic exchangecorrelation functionals can be developed independently and subsequently combined together without reparameterization.
 Publication:

Journal of Chemical Physics
 Pub Date:
 May 2012
 DOI:
 10.1063/1.4709609
 Bibcode:
 2012JChPh.136q4114S
 Keywords:

 density functional theory;
 electron correlations;
 exchange interactions (electron);
 hydrogen;
 vibrational states;
 31.15.eg;
 31.15.vj;
 33.15.Mt;
 33.20.Tp;
 Exchangecorrelation functionals;
 Electron correlation calculations for atoms and ions: excited states;
 Rotation vibration and vibrationrotation constants;
 Vibrational analysis