Electronic structure by quantum Monte Carlo methods: molecules, nanoclusters and solids
Lubos Mitas, Raleigh, North-Carolina, U.S.A
Lundi 10 juin 2002, 11h00
Quantum Monte Carlo (QMC) is a modern computational methodology for
efficient solving of quantum many-body problems. It is based on
a powerful combination of many-body wave functions and robustness
of Monte Carlo techniques. The talk will be focused on the electronic
structure QMC methods and their applications to real systems. The basic
notions of QMC, such as the correlated wave function construction,
variational and Green's function Monte Carlo methods will be briefly
explained. The QMC applications will include evaluations and predictions
of energy ordering of Si and C clusters [1,2,3], cohesive energies and
excitations in insulating solids [4,5,6], excitations in molecules [7],
barriers in chemical reactions [8], and structures of conjugated
carbon rings [9].
The applications will illustrate the main features of QMC: direct and
accurate treatment of electron correlation, wide range of applicability,
favorable scaling in the number of particles when compared with other
correlated methods and scalability on parallel architectures. Perhaps even
more important than accurate "numbers" are new insights into the behavior
of interacting quantum particles. Recasting of the Schrodinger equation
into a stochastic process enables to capture many-particle effects in
a very efficient manner and sheds new light on the nature of the correlation
problem. The computational efficiency provides opportunities for studies
of large systems with hundreds of valence electrons. ie, beyond the reach
of traditional correlated wave function approaches. Finally, the current
developments and obtained results suggest that QMC has become a powerful
predictive tool and a new alternative for accurate electronic structure
calculations.
[1] L. Mitas, J.C. Grossman, I. Stich, J. Tobik, Phys. Rev. Lett. 84,
1479 ('00).
[2] J.C. Grossman, L. Mitas, K. Raghavachari, Phys. Rev. Lett. 75,
3870 ('95).
[3] J.C. Grossman, L. Mitas, Phys. Rev. Lett. 74, 1323 ('95).
[4] L. Mitas, Comp. Phys. Commun. 96, 107 ('96).
[5] L. Mitas and R.M. Martin, Phys. Rev. Lett. 72, 2438 ('94).
[6] W.M.C. Foulkes, L. Mitas, G. Rajagopal, R. Needs, Rev. Mod. Phys., 2001,
73, pp. 33-83
[7] J.C. Grossman, M. Rohlfing, L. Mitas, S.G. Louie, and M.L. Cohen,
Phys. Rev. Lett., 86, 472 (2001)
[8] J.C. Grossman, L. Mitas, Phys. Rev. Lett. 79, 4353 ('97).
[9] T. Torelli and L. Mitas, Phys. Rev. Lett. 85, 1702 ('00)