CCL:G: Freq and Stability

 Sent to CCL by: "David  Hose" [anthrax_brothers(_)hotmail.com]
 Anthony,
 You might want to read Chris Cramer's posting about this from 2007.
 http://ftp.ccl.net/chemistry/resources/messages/2007/06/14.012-dir/index.html
 You'll also find some other useful tips in the days prior to Chris' posting.
 > From personal experience, using a finer integration grid (int=ultrafine in
 G03) solves the problem
 of a number of small imaginary (<50 cm-1) frequencies.  However, you'll have
 to rerun all of other
 calculations for your series of compounds with the same grid size if you want to
 compare energies.
 Also, you'll have to take a hit on computational speed.
 Regards,
 Dave.
 ----------------
 Dear CCL,
 I've been running geometry optimizations and found stationary points. I have
 also been using SCF =
 QC (also UB3LYP/6-311+G(d,p) NOSYMM).
 How can I be sure that my final answer is a local minimum? When I perform a
 frequency job after
 the optimization, I sometimes obtain imaginary frequencies, suggesting an
 nth-order saddle point
 (n is the number of imaginary frequencies).
 Does this also have to do with the stability of my wavefunction? I have used the
 keyword
 Stable=Opt for verification. But I find that I can have both a stable
 wavefunction and imaginary
 frequencies. How do I then find true local minima?
 Also, is it possible to run both a STABLE and geometry OPT job with the same
 route? Or do I have to
 use the Link1 keyword? If so, is it possible to copy my checkpoint file through
 the route section?
 Thanks
 Anthony