Optimization of quantum Monte Carlo wavefunctions using analytical derivatives

Optimization of quantum Monte Carlo wave functions using analytical energy derivatives

An algorithm is proposed to optimize quantum Monte Carlo ~QMC! wave functions based on Newton’s method and analytical computation of the first and second derivatives of the variational energy. This direct application of the variational principle yields significantly lower energy than variance minimization methods when applied to the same trial wave function. Quadratic convergence to the local m...

Quantum Monte Carlo with very large multideterminant wavefunctions

An algorithm to compute efficiently the first two derivatives of (very) large multideterminant wavefunctions for quantum Monte Carlo calculations is presented. The calculation of determinants and their derivatives is performed using the Sherman-Morrison formula for updating the inverse Slater matrix. An improved implementation based on the reduction of the number of column substitutions and on ...

Optimising Wavefunctions for Use in Quantum Monte Carlo Calculations

Pfaffian pairing and backflow wavefunctions for electronic structure quantum Monte Carlo methods

We investigate pfaffian trial wavefunctions with singlet and triplet pair orbitals by quantum Monte Carlo methods. We present mathematical identities and the key algebraic properties necessary for efficient evaluation of pfaffians. Following upon our previous study Bajdich et al., Phys. Rev. Lett. 96, 130201 2006 , we explore the possibilities of expanding the wavefunction in linear combination...

MontePython: Implementing Quantum Monte Carlo using Python

We present a cross-language C++/Python program for simulations of quantum mechanical systems with the use of Quantum Monte Carlo (QMC) methods. We describe a system for which to apply QMC, the algorithms of variational Monte Carlo and diffusion Monte Carlo and we describe how to implement theses methods in pure C++ and C++/Python. Furthermore we check the efficiency of the implementations in se...