Finite Difference Methods for Numerical Orbitals
Conference on Finite Difference Methods for Numerical Orbitals
Date : 26/08/2015 10:30 - 26/08/2015 11:30
Lieu : Chimie - 512A seminar room
Orateur(s) : Prof. Jim TALMAN, Department of Applied Mathematics, Western University, London, ON, Canada N6A 5B7
Organisateur(s) : Benoît CHAMPAGNE
In spite of the ubiquitous use of gaussian orbitals in molecular orbital theory, there remains some interest in the development of alternative approaches.
In the work to be described the atomic orbitals are defined as products of radial factors and angular momentum eigenfunctions, and the radial factors are defined numerically on a radial mesh.
A central difficulty that arises is the calculation of the necessary multicenter integrals.
A solution of the Löwdin problem of expanding an angular momentum wave function centered at one point in terms of angular momentum wave functions centered at another point will be described.
A second problem concerns the densities associate with products of orbitals on different centers. A method to expand these products about an arbitrary intermediate center will also be described.
These two methods can be applied to compute the necessary multicenter integrals for a molecular calculation, and also to the optimization of the radial factors in, for example, RHF calculations. This results in the possibility of using much smaller basis sets.
In the second part of the talk a method to construct corrections to the approximate HF solutions on three-dimensional Cartesian meshes will be described briefly. The accuracies of the results are then constrained only by the mesh parameters.The method for computing these corrections can also be applied to computing response properties independently of any spectrum of virtual orbitals. Results for the polarizabilities of a number of small molecules will be given.
Contact :
Benoît CHAMPAGNE
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Ext. 4554
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benoit.champagne@unamur.be
Télecharger :
vCal