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Manuscript Title: Filtered propagator functional for iterative dynamics of quantum dissipative systems.
Authors: E. Sim, N. Makri
Program title: FPF
Catalogue identifier: ADER_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 99(1997)335
Programming language: Fortran.
Computer: Sun SPARC Station.
Operating system: Sun OS 5.5, IBM AIX v3, DEC UNIX V3.2D-1, IRIX 5.
RAM: 32M words
Word size: 32
Keywords: Quantum dynamics, Path integrals, System-bath hamiltonian, Dissipation, Reduced density matrix, Chemical kinetics, Molecular physics, Solid state physics, Other.
Classification: 7.7, 16.12.

Nature of problem:
Calculates the time evolution of the reduced density matrix for a quantum mechanical system coupled to a dissipative environment.

Solution method:
The program employs an iterative procedure to evaluate the discretized path integral expressin for the reduced density matrix of the system. The relevant propagator is a functional of statistically significant path segments that span the medium-induced memory length. Continuous and discrete systems are treated alike via the use of discrete variable representations. An adiabatic partitioning of the Hamiltonian allows fairly large time steps. Considerable acceleration of the calculation is accomplished with proper filtering procedures. The algorithm converges to the full quantum mechanical result.

Restrictions:
The environment must consist of harmonic oscillators and should have a continuous spectrum. It is assumed that the environment is initially at thermal equilibrium.

Running time:
Depends on the number of relevant systems states, the magnitude of the coupling parameters and the medium correlation time. Refer to Tables 4-6 for representative execution times.