MATERIAL PROPERTIES OF ONE-DIMENSIONAL SYSTEMS STUDIED BY PATH-INTEGRAL QUANTUM MONTE-CARLO SIMULATIONS AND AN ANALYTICAL MANY-BODY MODEL

Feynman path-integral quantum Monte Carlo (QMC) simulations and an ana lytic 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 der ive position-space quantities, while band structure properties are eva luated by combining QMC data with expressions derived in momentum (k) space. Bridging link between both representations is the quasi-chemica l approximation (QCA). Electronic charge fluctuations [(DELTAn(i)2)] a nd the fluctuations of the magnetic local moments [(DELTAs(i)2)] are s tudied as a function of the on-site density [n(i)] and correlation str ength, which is given by the ratio between two-electron interaction an d kinetic hopping. Caused by the non-analytic behaviour of the chemica l potential mu = partial derivative E/partial derivative [n(i)] (with E denoting the electronic energy), strict ID systems with an on-site d ensity [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 chi, effective electronic mass m and Knight shift kappa. m is enhanced by a bandwidth renormalization factor D0(-1), k appa by an element eta(K) mapping the additional localization of the c orrelated electrons in the presence of an external magnetic field B an d chi by the product D0(-1) eta(K). Available experimental data are di scussed in the light of the present theoretical findings.