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QCMP017. MOPAC-PC: A Microcomputer Version of
MOPAC (A General Molecular Orbital Package)
(Version 4.0)
by Santiago Olivella, Departament de Química
OrgO(a,½)nica, Facultat de Química,
Universitat de Barcelona, Martí i Franqués 1,
08028 Barcelona, Catalonia, Spain
MOPAC-PC is a microcomputer version of Stewart's MOPAC program (QCPE 455) with some additional features. It is written in IBM Professional FORTRAN-77 (PROFORT), version 1.00, and runs under MS-DOS (versions 2.1 or more recent) on IBM-PC and compatible systems with floating point math coprocessor. A 10 Mb hard disk, a 360 Kb floppy disk drive, and at least 512 Kb of RAM are required. The new features that MOPAC-PC incorporates are: (1) The new AM1 (Austin Model 1)1 Hamiltonian is included. AM1 parameters are currently available for C, H, O, N, F, Cl, Br, and I. (2) The MNDO parameters for lithium are included.2 (3) Four new key words (ALTER, ALTA, ALTB and GUESS) are included. These key words may be used to select a particular electronic configuration inopen-shellsystem calculations. (4) The errors in the code of MOPAC (QCPE 455) that were giving rise to incorrect results (i.e., energy partitioning in MINDO/3 calculations, localized eigenvectors, net atomic charges and dipole moments in calculations using key words BIRADICAL, EXCITED, CI etc.) have been corrected. In order to work on microcomputers with only 512 Kb of RAM, MOPAC-PC has been broken up into four programs or executable modules, each of which performs one of the four general classes of calculations of the original package. These are: MOPAC1: Performs normal geometry optimizations, reaction coordinate calculations and "SADDLE" transition-state searches. MOPAC2:Performs geometry optimizations using Bartel's Non-Linear Least-Squares gradient norm minimization method (key word NLLSQ). MOPAC3:Performs geometry optimizations using the McIver-Komornicki gradient norm minimization method (key word SIGMA). MOPAC4: Performs force-constant calculations (key word FORCE), including vibrational frequencies and thermodynamic quantities. Note that, in microcomputers equipped with 1 Mb or more of RAM, the entire MOPAC-PC may be assembled in one executable module. This module would be similar in functionality to the standard MOPAC executable image that runs on VAX 11/780 minicomputers. MOPAC-PC is distributed on two double-sided diskettes of 360 Kb that contain the entire source code (broken up by individual subroutines, 91 in total), four sample input data files and the output files that these input files produce, and a file that is a manual with the instructions on the use and installation of the program. Since any of the above-mentioned four executable modules cannot be held in one 360 Kb floppy disk, these modules are not contained in the MOPAC-PC distribution diskettes. The user, therefore, must create each one of the executable modules in the microcomputer core memory and then save the modules on the hard disk. Note:The largest molecule which can be dealt with in QCMP017 as QCPE distributes it is 7 heavy atoms and 7 light atoms. __________ References: 1. M.J.S. Dewar, E. G. Zoebisch, E. F. Healy, J.J.P. Stewart, J. Am. Chem. Soc., 107, 3902 (1985). 2.W. Thiel, personal communication (January, 1982). __________ FORTRAN 77 (IBM Professional FORTRAN) Lines of Code: 13,000 |