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We have a general interest in quantum and theoretical chemistry. The research described below focuses on solving the Schroedinger equation by using computer simulation methods.
The Schroedinger equation has locally singular potentials which have
to be canceled by the kinetic energy (electron-nuclear and electron-electron
cusps). Also, by virtue of the repulsion of like charges, each electron
influences the locations of all the others (electron correlation). These
effects must be reflected in the wavefunction, and it simply isn't efficient
to do this by taking combinations of Slater determinants with a finite
set of one-electron basis functions, as in the traditional
approaches. Furthermore, the traditional methods make huge computational demands for systems containing a large number of electrons, necessitating approximations or practical limits on the scale of the calculations.
Facilitated by the speed of modern computers, quantum Monte Carlo methods have been developed to complement the traditional methods. One statistically samples from a pre-specified, explicitly correlated wavefunction (depends explicitly upon the interelectronic distances) and thereby treats the various electron correlation effects explicitly. Other features of the exact wavefunction, such as the electron-electron and electron-nuclear cusps are also treated in a direct manner.
Our Monte Carlo research includes the following objectives::
accurate treatment of systems containing heavy atoms.
accurate computed physical properties other than the energy.
accurate estimation of the relativistic effects.
These efforts have a strong interdiscipinary flavour. Professor Rothstein has a cross appointment in the Department of Physics and can supervise students in either chemistry or physics.
At present our group consists of two undergraduate-level chemists: Ms. Heather Cuthbert and Mr. Jason Dwyer , and Mr. Martin Snajdr who is doing his MSc research in physics.
P. Langfelder, S.M. Rothstein, and J. Vrbik, "Diffusion Quantum Monte Carlo Calculation of Nondifferential Properties for Atomic Ground States", J. Chem. Phys. 107, 8525-8535 (1997).
S.M. Rothstein, "All-Electron Monte Carlo Calculations on Heavy Atom Systems", in Recent Advances in Quantum Monte Carlo Methods, ed. by W.A. Lester, Jr. (World Scientific, Singapore, 1997) pp 181-187
S.M. Rothstein, "Valence Hamiltonian for Quantum Monte Carlo: Dissociation Energy of CuH", Intern. J. Quantum Chem. 60, 803-808 (1996) and 61, 153 (1997).
P. Belohorec, S.M. Rothstein, and J. Vrbik, "Infinitesimal Differential Diffusion Quantum Monte Carlo Study of CuH Spectroscopic Constants", J. Chem. Phys. 98, 6401-6405 (1993).
H. Bueckert, S.M. Rothstein, and J. Vrbik, "Optimization of Quantum Monte Carlo Wavefunctions using Analytical Derivatives", Canad. J. Chem.70, 366-371 (1992).
H. Bueckert, S.M. Rothstein and J. Vrbik, "Relativistic Variational Monte Carlo", Chem. Phys. Lettr. 190, 413-416 (1992).
J. Vrbik, D.A. Legare, and S.M. Rothstein, "Infinitesimal Differential Diffusion Quantum Monte Carlo, Diatomic Physical Properties", J. Chem. Phys. 92,1221-1227 (1990).
This page is: http://chemiris.labs.brocku.ca/~chemweb/faculty/rothstein/
Revised: July 5, 2000
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