Orateur
Prof.
Dario Bressanini
(Universita' dell'Insubria, Como, Italy)
Description
Highly compact wave functions with a clear physical meaning for the He atom and He-like isoelectronic ions for Z=1-10 are written as a symmetrized product of exp[(ar+br2)/(1+r)] electron-nucleus terms and an electron-electron Jastrow factor to satisfy the correct asymptotic behavior both at short and large interparticle distances. Some parameters are chosen to satisfy exactly the cusp-conditions, while the others are optimized by variational Monte Carlo calculations. The wave function energy is within 2 millihartrees from the non relativistic limit in the entire Z range, improving previously published work on similar compact wave functions. We tested the validity of the “coalescence wave function” approximation. The Z-dependence of the optimized parameters allows us to write a general form of the wave function, using Z as an explicit parameter and four parameters independent from Z. We checked the validity of this wave function on the case Z=30.
For more than two electrons we investigate the nodal structures of atomic wave functions based on a product of spatial orbitals, namely Restricted, Unrestricted and Generalized Valence Bond wave functions. While the wave functions are different, their nodal structures are shown to be equivalent. This result is verified by fixed node-diffusion Monte Carlo simulations for atoms up to Ne. For 3 and 4 electrons we investigate the shape of the nodal structure while the nuclear charge approaches its critical value.
Auteur principal
Prof.
Dario Bressanini
(Universita' dell'Insubria, Como, Italy)
