The MCHF atomic-structure package. C.F. Fischer.

Title of program: ATSP_MCHF version 1.00
Catalogue identifier: ADLY
Ref. in CPC: 128(2000)635
Distribution format: tar gzip file
Operating system: Sun UNIX OS 5.2, LINUX 2.2.10
High speed store required: 64MK words
Number of bits in a word: 32
Peripherals Required: disc
Number of lines in distributed program, including test data, etc: 135733
Programming language used: Fortran
Computer: SUN Ultra 1

Other versions of this program:

 Cat. Id.  Title                             Ref. in CPC
 ABZU      MCHF_LIBRARIES                     64(1991)399                    
 ABZV      MCHF_GENCL                         64(1991)406                    
 ABZW      MCHF_NONH                          64(1991)417                    
 ABZX      MCHF_88                            64(1991)431                    
 ABZY      MCHF_BREIT                         64(1991)455                    
 ABZZ      MCHF_CI                            64(1991)473                    
 ACBA      MCHF_MLTPOL                        64(1991)486                    
 ACBB      MCHF_LSTR AND MCHF_LSJTR           64(1991)501                    
 ACLD      MCHF_AUTO                          74(1993)381                    
 ACLE      MCHF_HFS                           74(1993)399                    
 ACLF      MCHF_ISOTOPE                       74(1993)415                    

Nature of physical problem:
This package determines the energy and associated wave functions for states of atoms and ions in the multiconfiguration Hartree Fock (MCHF) approximation. Once radial functions have been determined, relativistic effects may be included through the diagonalization of the Breit-Pauli Hamiltonian. Given a wve function, various atomic properties can be computed such as E1, E2, .., M1, M2, ... transitions between LS or LSJ states, isotope shift constants, and hyperfine interactions. Autoionization and simple photoionization calculations can also be performed.

Method of solution
Wavefunctions are obtained using variational methods leading to systems of differential equations for radial functions and the matrix eigenvalue problem for expansion coefficients of configurations states. The radial functions are obtained using finite difference methods.

Reasons for the new version
The previoius version was published as a series of programs, each associated with specific co-authors. In this, the entire package is collected into a directory structure with a make_atsp script that illustrates how the application can be generated. Intel PC executables are provided for PC users who do not have a FORTRAN compiler. Included also is a simple continuum MCHF program [1] with one open channel and an associated photoionization program. Use of the program is described in the book [2].

Summary of revisions
Previously published programs together with two unpublished programs have been collected and placed either in lib_src or atsp_src source directories that include makefiles for the different objects. A test_run directory has been added with script files that, when executed produce, results that can be checked with similar information in the results directory. The make directory contains a make_atsp that will make the applications on many platforms.

Restrictions on the complexity of the problem
The restrictions are those of the previous publications. The README file explains the different parameter statements that determine the size of the problem. Many restrictions may be relaxed by changing the value of parameter statements, but the restriction of a maximum of 5 open shells is not easily overcome. A limited amount of non-orthogonality of orbitals is allowed.

Typical running time
A single and double double replacement expansion from the 2s22p23P term of carbon to the orbitals 2p, 3s, 3p, 3d leading to 69 configuration states, required a total of 3.0 seconds for both angular and radial calculations on a SUN Ultra 1.

Unusual features of the program
Intel PC executables are provided for those without a FORTRAN compiler running the LINUX operating system. Background theory for the execution of the various applications is presented in a book [2] with selected examples. A limited amount of non-orthogonality between orbitals is allowed in the calculation of atomic properties.


 [1] C. Froese Fischer and Jinhua Xi (unpublished).                      
 [2] C. Froese Fischer, T. Brage, and Per Jonsson, Computational Atomic  
     Structure: An MCHF Approach, Institute of Physics (Bristol) 1997.