title: Algorithm for linear response functions at finite temperatures: application to ESR spectrum of s=1/2 antiferromagnet Cu benzoate.
abstract: We introduce an efficient and numerically stable method for calculating linear response functions chi(q,omega) of quantum systems at finite temperatures. The method is a combination of numerical solution of the time-dependent Schrödinger equation, random vector representation of trace, and Chebyshev polynomial expansion of Boltzmann operator. This method should be very useful for a wide range of strongly correlated quantum systems at finite temperatures. We present an application to the ESR spectrum of s=1 / 2 antiferromagnet Cu benzoate.
authors.affiliation: Computational Science Division, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Iitaka
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Ebisuzaki