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Workshops

Quantum Monte Carlo meets Quantum Chemistry: new approaches for electron correlation

June 15, 2010 to June 18, 2010
Location : CECAM-USI, Lugano, Switzerland
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Metal-insulator transition of one-dimension Hydrogen chains: a Variational Monte Carlo study

Lorenzo Stella
Queen's University Belfast, United Kingdom

Coauthor(s) : Claudio Attaccalite (Institut Neel, CNRS/UJF, Grenoble, France) Angel Rubio (Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, San Sebastian, Spain andFritz-Haber-Institut der Max-Pl


Abstract

Metal-Insulator Transitions (MIT) due to long-range electron-electron correlations cannot be modelled by Density Functional Theory (DFT) in any local or semi-local approximation, while many-body techniques, e.g., Dynamical Mean-Field Theory (DMFT) and Quantum Monte Carlo (QMC), have been mostly applied to semiempirical models. In this work, we present an extensive ab-initio Variational Monte Carlo (VMC) study of Hydrogen chains, which provide a prototypical example of one-dimensional MIT. To this end, we have monitored the dependency of the complexpolarisability on the chain geometry by changing both the interatomic distances and the chain dimerisation. Our VMC findings give valuable analytic insights on the many-body wavefunction of the chains that can be used to model the long-range electron-electron correlations which drive the MIT. Quality of the results has beenbenchmarked against accurate Diffusion Monte Carlo (DMC) calculations. Finally, we discuss the possibility of developing novel DFT functionals which include the long-range electron-electron correlations responsible for the MIT of one-dimensional Hydrogen chains, and address the implications for more realistic three-dimensional systems.