## StrainBands: A Density Functional Theory-based Tool

StrainBands uses first-principles density functional theory to compute the bandstructures, densities of states, charge densities, and Wannier functions of semiconductors, in equilibrium, under pressure or strain, and under unaxial stress.

PWscf and Quantum-Espresso v3.2.2 are used to perform eclectronic structure calculations. Maximally-localised Wannier functions are calculated by Wannier90 v1.0.2

#### Contributors:

Josef Ringgenberg, Joydeep Bhattacharjee, Jeffrey B. Neaton, Jeffrey Grossman, Eric Schwegler

Go to StrainBands at the

## QWalk: Quantum Monte Carlo

Quantum Monte Carlo methods solve the Schrodinger equation for many electrons to high accuracy--exactly in some cases. In most implementations, it also has favorable scaling with system size, approximately the same as mean-field theories like density functional theory, although with a larger prefactor. This allows us to obtain accurate ground and excited state energies for realistic chemical systems. Quantities such as binding energies, reaction barriers, and band gaps are accurately simulated using QMC methods.

This tool provides a convenient way to learn about and compare the most common QMC methods: Variational Monte Carlo and Diffusion Monte Carlo. It uses as a backend QWalk, an open-source program that implements several QMC methods.

#### Contributors:

Lucas Wagner, Jeffrey Grossman, Jeffrey B. Neaton

Go to QWalk at the