TITLE:
An Improved Finite Temperature Lanczos Method and Its Application to the Spin-1/2 Heisenberg Model on the Kagome Lattice
AUTHORS:
Tomo Munehisa
KEYWORDS:
Finite Temperature Lanczos Method, Heisenberg Model, Kagome Lattice, Specific Heat
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.4 No.3,
August
26,
2014
ABSTRACT:
We present an improvement
of the finite temperature Lanczos method in order to apply this method to systems at very low temperature. One proposal is to
introduce two steps in this method. In the first step, we use the
Chebyshev polynomial expansion to calculate exp(-H/T1) random vector>at moderate
temperature T1. In the second step, we apply the ordinary finite
temperature Lanczos method using the calculated state as the initial state of
the Lanczos method. Another proposal is to employ a sampling method for
selecting a random vector. By this sampling, we can improve an efficiency of
calculations. Using the improved finite temperature Lanczos method, we
calculate the specific heat of the spin-1/2 Heisenberg model on the kagome
lattices of 27 and 30 sites.