PROGRAM SUMMARY
Title of program:
RELCI
Catalogue identifier:
ADQH
Ref. in CPC:
148(2002)103
Distribution format: tar gzip file
Operating system: IBM AIX 4.1.2+, Linux 6.1.+
Number of bits in a word:
64
Peripherals Required: disc
Number of lines in distributed program, including test data, etc:
189696
Keywords:
Atomic physics, Breit interaction, Configuration interaction,
Dirac-Coulomb-Breit Hamiltonian, Large-scale computations,
Multiconfiguration Dirac-Fock, QED estimate, Relativistic,
Transverse interaction, Structure.
Programming language used: Fortran
Computer:
IBM RS 6000 ,
PC Pentium III .
CPC Program Library subprograms used:
Cat. Id. Title Ref. in CPC ADCU GRASP92 94(1996)249
Nature of physical problem:
Approximate atomic wave functions are determined by diagonalizing the
Hamiltonian matrix within an appropriate many-particle basis. Here, the
construction of the configuration interaction (CI) basis follows the
same principles as in the structure code GRASP92 [1] which is utilized
to generate the configuration state functions (CSF) and the radial
orbitals for all subshells of the given active space.
Restrictions:
The size of useful CI expansions critically depends on the shell
structure of the atom or ion under consideration. Wave function
expansions of several ten (or even hundred) thousand CSF are currently
feasible on standard PCs. For more than two equivalent electrons,
antisymmetrized subshell states are supported only for j <= 9/2 (i.e.
for all shells up to the g9/2 or h9/2 subshells).
Unusual features:
RELCI is designed as part of the RATIP package [2,3] for the calculation
of relativistic atomic transition and ionization properties. An
interactive dialog at the beginning of the execution enables the user to
specify the (relativistic) interactions among the electrons and the mode
of computation. A number of different modes are supported with regard
to the re-use and maintenance of the internal storage. While the
implementation of the program follows lines similar to GRASP92, still,
the RELCI program has been rewritten entirely to conform to the new
Fortran 90/95 standard [4] and to meet the requirements of modern
applications. By using a dynamic allocation of all important arrays,
there are no restrictions any more with regard to the numbers of open
shells (within a single CSF) or individual subshells. When compared
with RCI92 for their run-time behaviour, our new RELCI program is faster
by a factor between 3 ... 8, depending on the particular application.
Typical running time:
8 minutes on a 550 MHz Pentium III processor.
Additional comments:
Memory required Memory requirements strongly depend on the size
of the Hamiltonian matrix and the selected mode of computation.
Number of bits in a word All real variables are parametrized by a
'selected kind parameter' and, thus, can easily be adapted to any
required precision as supported by the compiler. Presently, the 'kind'
parameter is set to double precision (two 32-bit words) in the module
'rabs_constant'.
References:
[1] F.A. Parpia, C.F. Fischer, and I.P. Grant, Comput. Phys. Commun.
94 (1996) 249.
[2] S. Fritzsche, J. Elec. Spec. Rel. Phen. 114-116 (2001) 1155.
[3] S. Fritzsche, C.F. Fischer, and C.Z. Dong, Comput. Phys. Commun.
124 (2000) 343.
[4] M. Metcalf and J. Reid, Fortran 90/95 Explained (Oxford University
Press, 1996).