Program BO-SPIN, Version 1.01 I. Mayer Chemical Research Center, Hungarian Academy of Sciences H-1525 Budapest, P.O.Box 17, Hungary This program performs bond order and valence analysis of the ab initio SCF wave functions (RHF or UHF) produced by the widely used "Gaussian" system (G92,... G03) as well as the analysis of spin-distribution (spin populations and decomposition of in terms of atomic and diatomic contributions) for single determinant wave functions. In the case of DFT calculations, the single determinant built up of the Kohn-Sham orbitals is considered. This program may be used for large systems, too. Bond order and valence indices represent LCAO counterparts of the respective classical chemical parameters; they were introduced in I. Mayer, Chem. Phys. Lett. 97, 270, 1983 (closed shell), ibid. 117, 396, 1985 (open shell); also see IJQC 29, 73, 1986. The decomposition of the expectation value of S^2 is performed according to the definition of local spins described in I. Mayer, CPL 440, 357, 2007. (In the closed-shell case all spin-dependent quantities vanish and are not computed therefore.) The program incorporates some routines from I. Mayer and A. Hamza, Program APOST, Budapest 2000. The basis bond order and valence routine was written by I. Mayer, Budapest. 1982/83. Installation of the program: The "tar" file contains all the necessary FORTRAN source files as well as a "Makefile", which should be appropriate to produce the executable by issuing the command "make" on a UNIX or Linux system. (If necessary, replace the call to "f77" in the Makefile by the name of your FORTRAN compiler.) The name of the executable generated is "bospin". Usage of the program: The only input required by the program is the "formatted checkpoint file" (Test.FChk) which is produced by the Gaussian, provided that the FormCheck keyword is included in the Gaussian input. In the program the file Test.FChk is used for input as the FORTRAN file fort.14, and is copied to file "Tmp" for actual processing (file fort.15). An alternative is to conserve the binary checkpoint file which is produced during the Gaussian run (include %chk="filename" in the input) and to format it by using the command "formchk" which is a part of the Gaussian system. The formatted checkpoint file should then be renamed (copied) to Test.Fchk (or to fort.14, if the statement "open(14,file='Test.FChk')" has been deleted from "subroutine input". A convenient way of using the program is to include it in the script performing the Gaussian run; one should take care of ensuring that "BO-SPIN5" should NOT start before Gaussian is finished. It is desirable to delete or rename the formatted checkpoint file Test.FChk after the calculation, in order to avoid its unwanted reuse. Cite this program as: I. Mayer, Program "BO-SPIN", Version 1.01 (Chemical Research Center, Hungarian Academy of Sciences), Budapest, 2007. Limitations: This version of the program is applicable up to 100 atoms, 2000 basis orbitals and 10000 primitive Gaussians These numbers can easily be extended further by increasing every parameter, which is equal 100, 101, 2000 or 10000. Bugs etc. Please report bugs, problems etc. to the e-mail address above - we will try our best to help you.