Material properties of one-dimensional systems studied by path-integral quantum Monte Carlo simulations and an analytical many-body model
Michael C. Böhm, Joachim Schulte, Luis Utrera
Feynman path-integral quantum Monte Carlo (QMC) simulations and an analytic many-body approach are used to study the ground state properties of one-dimensional (1D) chains in the theoretical framework of model Hamiltonians of the Hubbard type. The QMC algorithm is employed to derive position-space quantities, while band structure properties are evaluated by combining QMC data with expressions derived in momentum (k) space. Bridging link between both representations is the quasi-chemical approximation (QCA). Electronic charge fluctuations <(Δn 2 i )> and the fluctuations of the magnetic local moments <(Δs 2 i )> are studied as a function of the on-site density <n i > and correlation strength, which is given by the ratio between two-electron interaction and kinetic hopping. Caused by the non-analytic behaviour of the chemical potential μ = ∂E/∂<n i > (with E denoting the electronic energy), strict 1D systems with an on-site density <n i > of 1·0 do not exhibit the properties of a conductor for any non-zero interaction beyond the mean-field approximation. The QMC simulations lead to straightforward access to the probabilities P i (n) of finding n = 0, 1, 2 electrons at the ith lattice site. The P i (n) elements allow to calculate the enhancement factors on the electron spin susceptibility χ, effective electronic mass m* and Knight shift κ. m* is enhanced by a bandwidth renormalization factor D -1 0, κ by an element ηK mapping the additional localization of the correlated electrons in the presence of an external magnetic field B and χ by the product D -1 0 ηK. Available experimental data are discussed in the light of the present theoretical findings.
Molecular Physics•Aug 20, 1993•14 citations