First Principles Description of Strongly Correlated Electrons Using Quantum Monte Carlo

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

TECHNICAL SUMMARY This award supports computational and theoretical research and education to advance quantum Monte Carlo methods and study strongly correlated materials. The PI will calculate reduced density matrices from accurate quantum Monte Carlo calculations and use the information to develop a method to determine the nature of correlations in strongly correlated materials. The study of the metal-insulator transition in Vanadium dioxide will be a specific focus of study. The PI will use the methods to peform a survey of various correlated materials, including the cuprate superconductors. The PI aims to develop a model for the dependence of correlation on doping that will lead to a low-energy model for high temperature superconductor materials. As a result of this work, both publications and computer code to perform the calculations will be broadly distributed in the form of the open source program QWalk. This project will also train students in advanced computational modeling of strongly correlated materials at the frontiers of materials research. NON-TECHNICAL SUMMARY This award supports computational and theoretical research to develop methods to gain insight into strongly correlated materials that exhibit correlations in the motion of electrons that arise from strong interactions between electrons. The research will focus on two classes of materials, vanadium dioxide and high temperature superconductors. It is thought that strong interactions between electrons lead to vanadium dioxide turning from a metal to an insulator. The high temperature superconductors exhibit superconductivity, a state of matter which can conduct electricity without loss, up to the highest temperatures at which superconductivity has been observed. It is believed that electron correlations are an important ingredient to achieving high temperature superconductivity. The PI wil develop a method based on the solution of the fundamental equation of quantum mechanics, the Schroedinger equation for a large number of electrons. The PI will use advanced methods to solve the equation with a minmum number of assumption which is computationally very intense. The PI will develop a method for analyzing the results which will provide information that can be used to develop a simplified model that is more computationally tractable. As a result of this work, both publications and computer code to perform the calculations will be broadly distributed in the form of the open source program QWalk. This project will also train students in advanced computational modeling of strongly correlated materials at the frontiers of materials research.