PROGRAM SUMMARY
Title of program:
SCRMTRX
Catalogue identifier:
ADRB
Ref. in CPC:
151(2003)199
Distribution format: tar gzip file
Operating system: Linux, UNIX
High speed store required:
149K words
Number of bits in a word:
8
Number of lines in distributed program, including test data, etc:
35472
Keywords:
Screened Coulomb potential, Excitation, Transition matrix element,
Ion-atom collision, Modified Bessel functions of half
integer order, Derivatives of the modified Bessel functions of half
integer order, Atomic physics, Other.
Programming language used: Fortran
Nature of physical problem:
The electronic screening effect plays an important role in ion-atom
collisions. Atomic or molecular transitions are often induced by the
screened Coulomb potentials of atoms or partially ionized ions. The
corresponding screening matrix elements are often required in
theoretical descriptions. The SCRMTRX program calculates such screening
matrix elements for bound-bound transitions for arbitrarily chosen
target wave functions.
Method of solution:
The calculation of the screening function is based on a multipole
expansion series using the derivatives of the modified Bessel functions
of half integer order. The program includes subroutines for calculating
In+1/2(x) and Kn+1/2(x) and their derivatives in a wide range of n and
x.
Restrictions:
The screening matrix element is considered as independent of the
azimuthal coordinate of the internuclear distance.
Typical running time:
The calculation of the screening matrix element for a given internuclear
distance is about 0.3s depending on the transition and the accuracy
demands. The test calculations were made on a computer with 265 MB
memory and a 800 MHz AMD processor.