## Quantum Monte Carlo Simulations for Real
Materials

The starting point for understanding the properties of atoms,
molecules and solids is the many-electron Schrodinger
equation. Solving this equation is a theoretically challenging and
computationally demanding problem, and one of the most promising
approaches is the use of statistical techniques known as quantum Monte
Carlo (QMC) methods. QMC methods come in variety of flavours, and we
use the variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC)
methods. These are very promising for applications to condensed
matter because (i) they give an accurate description of electron
correlation effects and (ii) the computational cost scales well with
system size, normally something like the qsuare or the cube of the
number of atoms. VMC and DMC calculations have been applied to
systems containing over 1000 electrons.

The standard approach to electronic structure computation has been the
use of mean-field methods such as Hartree-Fock and local density
functional theory. These methods have been outstandingly successful,
but the mean-field picture is not always accurate enough to give a
proper physical understanding. Our QMC techniques use the mean-field
approximation as a starting point for the calculations, but they also
include an explicit and accurate description of correlation effects.

We perform our calculations using the CASINO code.
We have applied QMC techniques to calculating ground and excited state
energies of solids and molecules, including studies of defects in
solids, solid surfaces, relativistic effects, phase transitions, and
calculations aimed at developing new density functionals.

## Other information

Publications list
Theory of Condensed Matter
Group -- Home Page

© Richard Needs