More g92 isotope problems

[Louis.Grace at.at um.cc.umich.edu]

 Hello, network!
      I would like to thank everyone who responded to my question about
 format of the input file to do isotopic substitution for a frequency
 calculation under Gaussian92(TM).  My problem arose from the fact that the
 g92 brochure's example merely states that in g92 one does not need the
 "NO" line.  It does not mention, though, that one needs the
 temperature and
 pressure!  When I put these in, it seemed to read the file o.k.  Thanks!
      Now I have another problem.  While g92 seems to be getting all the
 atom coordinates, and it tells me it has read the isotopic masses, the
 force constants are all ZERO!  I have been using the following command line:
 (sorry, lines:)
 "%chk=benzene.chk"
 "#hf/3-21g test freq=(readfc,readisotopes) guess=read geom=check"
 (The quotes are because I'm on an IBM mainframe with a STUPID operating system
 that tries to interpret the % sign as a command!)
      Anyway, the output seems to contain the standard orientation and reduced
 masses, but, as I said, the force constants, energies and frequencies are all
 zero.  What could be the problem?  The checkpoint file was generated in a run
 for which the command line was just:
 #hf/3-21g opt test
      Did I need anything else?  Could the checkpoint file be screwed up?
 Is there possibly another keyword I'm missing in the isotope run?
      Thanks in advance to anyone who can help.
                                              Louis Grace
                                              Chemistry Department
                                              The University of Michigan
                                              Ann Arbor, Michigan   48104