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Manuscript Title: Efficient hybrid algorithm for the dynamic creation of wormlike chains in solutions, brushes, melts and glasses.
Authors: M. Kroger
Program title: GenPol
Catalogue identifier: ADJU_v1_0
Distribution format: tar.gz
Journal reference: Comput. Phys. Commun. 118(1999)278
Programming language: Fortran.
Computer: Silicon Graphics.
Operating system: UNIX, Linux.
RAM: 1M words
Word size: 16
Keywords: Wormlike chains, Semiflexible polymers, Melts, Solutions, Brushes, Algorithm, Solid state physics, Other.
Classification: 7.7.

Nature of problem:
The problem is to place and relax flexible, semiflexible or stiff, tethered or free model polymer chains within a finite volume with periodic boundaries such that the configurational statistics is obtained from a microscopic potential which determines the local and - affected by concentration and excluded volume - global conformational features of the system in a 'physical' way. The resulting configuration obeys a minimum distance criterion.

Solution method:
In a first step, according to the chosen system parameters, a mixture of phantom and excluded volume chains plus solvent particles are placed into the (finite and final) simulation box by a Monte Carlo algorithm. A subsequent molecular dynamics algorithm solves Newton's equations of motion during the relaxation phase, while the strength of the repulsive and attractive forces, the temperature and integration time step control interact with each other by a global optimization procedure which minimizes the CPU request for the goals i) the minimum distance between particles is reaching (finally above) its lower limit and ii) the changes in both local and global conformational properties - as determined by the Monte Carlo procedure - are kept at a very low level. The algorithm interrupts the relaxation process when a break off condition (actually the minimum distance criterion) is fulfilled.

Restrictions:
None, except that the machine must provide the needed main memory (see Sec. 3).

Running time:
The typical running time increases with the bulk density and the minimum separation distance and is linearly increasing with system size. The creation time is of the order of 0.04-0.05 seconds per monomer on a SGI Octane (R10000, 195 MHz) workstation. See the Sec. 4 'Benchmarking' for explicit CPU times.