Nonlinear Phenomena in Complex Systems, 2004, Vol.7, No.4, pp.377-384

NONLINEAR PHENOMENA IN COMPLEX SYSTEMS
An Interdisciplinary Journal

2004, Vol.7, No.4, pp.377-384

Nonperturbative Algorithm for Density Matrix Calculation.
I.D.Feranchuk, A.A.Ivanov

The operator method and the cumulant expansion are used for nonperturbative calculation of the density matrix and its diagonal elements. The systematic procedure for calculation of these values for a quantum system is considered. Some numerical results are also obtained for the quantum anharmonic oscillator.
Key words: nonperturbative, cumulant, density matrix

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