TY - JOUR

T1 - Non-Born-Oppenheimer treatment of the H 2 Hookean molecule

AU - Ludeña, Eduardo V.

AU - Lopez, Xabier

AU - Ugalde, Jesus M.

N1 - Funding Information:
One of the authors (E.V.L.) would like to acknowledge Professor P.M. Echenique and Professor J.M. Ugalde for their kind hospitality and the Basque Government for financial support during his stay in Donostia. He also acknowledges support from Fonacit of Venezuela through Group Project No. G97000741. Two of the authors (J.M.U. and X.L.) gratefully acknowledge financial support from Eusko Jaurlaritza (Basque Government) and the Spanish Office for Scientific Research. The SGI/IZO-SGIker UPV/EHU (supported by the National Program for the Promotion of Human Resources within the National Plan of Scientific Research, Development and Innovation-Fondo Social Europeo and MCyT) is greatfully acknowledged for generous allocation of computational resources. This work is dedicated to Professor Cecilia Sarasola.

PY - 2005

Y1 - 2005

N2 - We show that the exact non-Born-Oppenheimer Schrödinger equation for the Hookean diatomic molecule H2 (a two-proton, two-electron system where the electron-proton interaction is harmonic while the proton-proton and electron-electron interactions are Coulombic) can be decoupled into equations describing the relative motion of the electrons, the relative motion of nuclei, the motion of a collective mode representing a three-dimensional harmonic oscillator, and the motion of a free particle expressed as a linear combination of the individual center-of-mass coordinates of the nuclei and electrons. Analytic solutions to the relative motion of electrons can be readily obtained for the given values of the harmonic coupling constant. However, exact analytic solutions to the equation for the relative motion of the nuclei cannot be obtained simultaneously due to the fact that the harmonic constants in these two equations are coupled. For this reason, we present for the relative nuclear motion approximate analytic wave functions, one of them obtained variationally and the other by a series solution where the coefficients are determined recursively. We also explore a variational solution to the Taylor-series expansion of the nuclear interaction potential. Properties of the electronic and nuclear intracule densities are examined at different values of the coupling constant. An interesting result of the present non-Born-Oppenheimer treatment of this harmonic model is the fact that the relative nuclear motion occurs in a highly correlated regime. This leads in a natural way to a spatial localization of the nuclei akin to Wigner electronic crystallization.

AB - We show that the exact non-Born-Oppenheimer Schrödinger equation for the Hookean diatomic molecule H2 (a two-proton, two-electron system where the electron-proton interaction is harmonic while the proton-proton and electron-electron interactions are Coulombic) can be decoupled into equations describing the relative motion of the electrons, the relative motion of nuclei, the motion of a collective mode representing a three-dimensional harmonic oscillator, and the motion of a free particle expressed as a linear combination of the individual center-of-mass coordinates of the nuclei and electrons. Analytic solutions to the relative motion of electrons can be readily obtained for the given values of the harmonic coupling constant. However, exact analytic solutions to the equation for the relative motion of the nuclei cannot be obtained simultaneously due to the fact that the harmonic constants in these two equations are coupled. For this reason, we present for the relative nuclear motion approximate analytic wave functions, one of them obtained variationally and the other by a series solution where the coefficients are determined recursively. We also explore a variational solution to the Taylor-series expansion of the nuclear interaction potential. Properties of the electronic and nuclear intracule densities are examined at different values of the coupling constant. An interesting result of the present non-Born-Oppenheimer treatment of this harmonic model is the fact that the relative nuclear motion occurs in a highly correlated regime. This leads in a natural way to a spatial localization of the nuclei akin to Wigner electronic crystallization.

UR - http://www.scopus.com/inward/record.url?scp=23444434492&partnerID=8YFLogxK

U2 - 10.1063/1.1940611

DO - 10.1063/1.1940611

M3 - Artículo

AN - SCOPUS:23444434492

SN - 0021-9606

VL - 123

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

IS - 2

M1 - 024102

ER -