2008/06/25 by Fabio Sterpone, Sterpone, Fabio, Leonardo Spanu +7 · 1 citation
Physics and Astronomy · #Advanced Chemical Physics Studies #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Other Condensed Matter (cond-mat.other) #Spectroscopy and Quantum Chemical Studies
paper · pdf · doi:10.48550/arxiv.0806.4169
openalex publication_date 2008/06/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a variational MonteCarlo (VMC) and lattice regularized diffusion MonteCarlo (LRDMC) study of the binding energy and dispersion curve of the water dimer. As a variation ansatz we use the JAGP wave function, an implementation of the resonating valence bond (RVB) idea. Actually one the aim of the present work is to investigate how the bonding of two water molecules, as a prototype of the hydrogen-bonded complexes, could be described within an JAGP approach. Using a pseudopotential for the inert core of the Oxygen, with a full optimization of the variational parameters, we obtain at the VMC level a binding energy of -4.5(0.1) Kcal/mol, while LRDMC calculations gives -4.9(0.1) Kcal/mol (experiment 5 Kcal/Mol). The calculated dispersion curve reproduces both at the VMC and LRDMC level the miminum position and the curvature.The quality of the WF gives us the possibility to dissect the binding energy in different contributions by appropriately switching off determinantal and Jastrow terms in the JAGP: we estimate the dynamical contribution to the binding energy to be of the order of 1.4(0.2) Kcal/Mol whereas the covalent contribution about 1.0(0.2) Kcal/Mol. JAGP reveales thus a promising WF for describing systems where both dispersive and covalent forces play an important role.