PROGRAM SUMMARY
Title of program:
kb
Catalogue identifier:
ADKQ
Ref. in CPC:
123(1999)123
Operating system: UNICOS, IRIX 6.4
High speed store required:
60MK words
Number of bits in a word:
64
Number of lines in distributed program, including test data, etc:
1432
Programming language used: Fortran
Computer: CRAY C90
Nature of physical problem:
The output of this program describes the thermalisation by internal
collisions in a nonrelativistic infinite fermion system. It is most
useful when applied to situations where the time scales of relaxation,
individual collisions and quantum coherence are overlapping: some
examples are nuclear heavy ion collisions and femtosecondscale carrier
kinetics in excited semiconductors.
Method of solution
The equations are solved on a momentum grid, marching along both axes in
the two-time plane. The bulk of the processing time is spent in the
time-stepping and evaluating the collision integrals. The time-stepping
is done by a two-pass iteration, while the collision integrals are
computed by Fast Fourier Transform.
Typical running time
The running time depends mainly on the parameter ntimes. Table 1 shows
the running times on the Cray C90 of the Pittsburgh Supercomputing
Center and on the SGI of the University of Arizona Center of Computing
and Information Technology. The Cray C90 has 16 processors with a peak
aggregate speed of 16 Gflops, and a main memory of 512 Mwords or
4 Gbytes. The calculations of Table 1 were made for the nuclear case
and for the following parameters: ntl=61, nq=4620, nvec=48 and
mod_store=3 (cylindrical symmetry). Serial processing on one processor
was used.
Unusual features of the program
The program uses the three dimensional Fast Fourier Transform routine
CFFT3D of the SGI library or the subroutine CCFFT3D of the Cray library.
References
[1] SGI library. [2] Cray library.