last modified: 15-OCT-1987 | catalog | categories | new | search |

NEA-0508 RHFPPP.

RHFPPP, SCF-LCAO-MO Calculation for Closed Shell and Open Shell Organic Molecules

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1. NAME OR DESIGNATION OF PROGRAM:  RHFPPP.
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2. COMPUTERS
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Program name Package id Status Status date
RHFPPP NEA-0508/01 Tested 15-OCT-1987

Machines used:

Package ID Orig. computer Test computer
NEA-0508/01 UNIVAC 1110 UNIVAC 1100
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3. NATURE OF PHYSICAL PROBLEM SOLVED

Complete program performs SCF-LCAO-MO calculations for both closed and open-shell organic pi-molecules. The Pariser-Parr-People approximations are used with-  in the framework of the restricted Hartree-Fock method. The SCF calculation is followed, if desired, by a variational configuration  interaction (CI) calculation including singly excited configura- tions.
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4. METHOD OF SOLUTION

A standard procedure is used; at each step a real symmetric matrix has to be diagonalized. The self-consistency is checked by comparing the eigenvectors between two consecutive steps.
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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

  i) The calculations are restricted to planar molecules.
ii) In order to avoid accumulation of round-off errors, in the iterative procedure, double precision arithmetic is used.
iii) The program is restricted to systems up to about 16 atoms;  however the size of the systems can easily be modified if required.
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6. TYPICAL RUNNING TIME

The running time depends on the calculations which are performed (SCF only or SCF+CI). In the SCF part the running time depends strongly on the particular system under consideration, because of the iterative procedure, and also on the accuracy required for the self-consistency. In the CI part the running time depends on the number of configurations which are taken into account in the CI matrix. For example, for a molecule of  eight atoms where self-consistency is reached (up to 10(-7)) after about ten iterations and where all singly excited states are in- cluded in the CI calculations, the running time is about two minutes.
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7. UNUSUAL FEATURES OF THE PROGRAM

i) For systems which have the point group symmetry D2H, the  symmetry of excited states is determined and the allowed transitions are then obtained. Moreover the size of the CI matrix is reduced by symmetry. This allows taking account of a great number of configurations and determining directly allowed transitions after CI.
ii) It is possible to choose the types and the number of configurations which are to be included in the CI matrix.
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8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS
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9. STATUS
Package ID Status date Status
NEA-0508/01 15-OCT-1987 Tested at NEADB
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10. REFERENCES

- R. McWeeny and B.T. Sutcliffe:
  Methods of Molecular Quantum Mechanics
  (Academic Press, New York,1969).
- H.J. Monkhorst and J. Kommandeur:
  J.Chem.Phys. 47(1967) 391.
- R. Zahradnich and P. Carsky:
  J.Phys.Chem. 74(1970) 1235.
- J. Wasiliewski:
  ACTA Phys. Polon. A38 (1970) 349.
- A. Bieber and J.J. Andre:
  Chem.Phys. 5(1974) 166 and references therein.
- A. Bieber and J.J. Andre:
  Chem.Phys. 7(1975) 137.
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11. MACHINE REQUIREMENTS

The amount of high speed memory which is needed depends strongly on the size of the system and of the number  of configurations retained in the CI matrix. For example for a system of sixteen atoms, with a D2H point group symmetry, a CI calculation including all singly excited states requires 35k words when the  overlay structure is used.
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12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
NEA-0508/01 FORTRAN-IV
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13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

EXEC 8 of the UNIVAC 1100 series. No additional subroutine library is needed.
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14. ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:  An overlay structure is available for this programme.
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15. NAME AND ESTABLISHMENT OF AUTHOR

     A. Bieber and J.J. Andre
     Centre de recherches sur les Macromolecules (C.N.R.S)
     6, rue Boussingault
     67083 Strasbourg Cedex (France)
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16. MATERIAL AVAILABLE
NEA-0508/01
File name File description Records
NEA0508_01.001 Information file 46
NEA0508_01.002 Control information and JCL 19
NEA0508_01.003 RHFPPP Source Program 3905
NEA0508_01.004 RHFPPP Input Sample Problem 109
NEA0508_01.005 RHFPPP Output Sample Problem 1616
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17. CATEGORIES
  • U. Chemistry
  • W. Physics

Keywords: molecules, shells.