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Title: Exchange and spin states in quantum dots under strong spatial correlations. Computer simulation by the Feynman path integral method

The fundamental laws in the behavior of electrons in model quantum dots that are caused by exchange and strong Coulomb correlations are studied. The ab initio path integral method is used to numerically simulate systems of two, three, four, and six interacting identical electrons confined in a three-dimensional spherical potential well with a parabolic confining potential against the background of thermal fluctuations. The temperature dependences of spin and collective spin magnetic susceptibility are calculated for model quantum dots of various spatial sizes. A basically exact procedure is proposed for taking into account the permutation symmetry and the spin state of electrons, which makes it possible to perform numerical calculations using modern computer facilities. The conditions of applicability of a virial energy estimator and its optimum form in exchange systems are determined. A correlation estimator of kinetic energy, which is an alternative to a basic estimator, is suggested. A fundamental relation between the kinetic energy of a quantum particle and the character of its virtual diffusion in imaginary time is demonstrated. The process of natural 'pairing' of electron spins during the compression of a quantum dot and cooling of a system is numerically reproduced in terms of path integrals. The temperaturemore » dependences of the spin magnetic susceptibility of electron pairs with a characteristic maximum caused by spin pairing are obtained.« less
Authors:
 [1]
  1. St. Petersburg State Polytechnic University (Russian Federation)
Publication Date:
OSTI Identifier:
22210400
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Experimental and Theoretical Physics; Journal Volume: 117; Journal Issue: 4; Other Information: Copyright (c) 2013 Pleiades Publishing, Inc.; http://www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPUTERIZED SIMULATION; COULOMB FIELD; ELECTRON PAIRS; ELECTRONS; FEYNMAN PATH INTEGRAL; FLUCTUATIONS; KINETIC ENERGY; MAGNETIC SUSCEPTIBILITY; POTENTIALS; QUANTUM DOTS; SPHERICAL CONFIGURATION; SPIN; TEMPERATURE DEPENDENCE; THREE-DIMENSIONAL CALCULATIONS