More re MOPAC IR

 Dear Colleagues;
      A few days ago I posted a query about how to implement MOPAC for the gene-
 ration of IR spectra.  I thank the handful of people who took the time and ef-
 fort to respond.  In a nutshell, one simply has to add the keyword FORCE, and
 a vibrational analysis will be added to the MOPAC output.  (n.b.: In my imple-
 mentation of MOPAC 6.0, at least, the keywords FORCE and EF seem to be incompat-
 ible.  Does anyone know why that might be?)   One responder mentioned a very
 nice programme by Dr. J. Gosper of Brunel University (U. K.) which visualises
 the output structure from a MOPAC .out file and which can animate one vibration-
 al frequency at a time.  Unfortunately, I do not believe that there yet exists
 a programme that will regenerate an IR spectrum as such from the output of a
 MOPAC "FORCE" calculation.  (If I am wrong, kidly correct me.)
      As a result of the responses received, I was able to undertake an intelli-
 gent search through the local science libraries, and found a particularly use-
 ful article:
      SEEGER, D. M., KORZENIEWSKI, C., and KOWALCHYK, W., Evaluation of
      vibrational force fields derived by using semiempirical and ab
      initio methods.  J. Phys. Chem. 95: 6871-6879.
 which lists experimental, semiempirical, and ab initio force constants and fre-
 quencies for a variety of molecules, as well as recommended sacling factors for
 different types of vibrations calculated using the MNDO, AM1, and PM3 parametri-
 sations.  One of the responders mentioned that a Dr. Radom (Leo Radom?) has pub-
 lished, or has in press, an article further detailing vibrational frequency
 scaling factors for MOPAC- and ab initio-calculated molecular vibrational fre-
 quencies.  However, I have been unavble to locate such an article.  Does anyone
 out there know about this paper?  If so, kindly post details.
      I now wish to follow up my original query about MOPAC and IR with these
 two questions:
      (i) The article cited above by Seeger et al. calculated MNDO, AM1, and PM3
 scaling factors for hydroxyl O -- H stretches based only upon water.  I am par-
 ticularly interested in a scaling factor for hydroxyl O -- H stretches in phenol
 and phenolic-type molecules,  both  simple (cresols, xylenols, methoxyphenols)
 and more complex (terpenoids, oestrogens, &c.).  Has anyone seen an article
 in
 which a scaling factor for phenolic O -- H stretches is provided?
     (ii) In connection with the above, I am seeking values for phenolic O -- H
 stretching frequencies with reference to particular orientations of the phenolic
 hydroxy moieties vis-a'-vis the rest of the molecule.  For example, in an old
 paper by Simonyi et al [Tetrah. Lett. (19): 1631-1632 (1975), the authors sug-
 gest that for 2,6-di-isopropylphenol the O -- H peak at 3641 cm-1 corresponds
 to the structure in which the hydroxy moiety is captured between the two methyls
 of the isopropyl unit, whereas the O -- H stretch at 3619 cm-1 is due to
 "a"
 conformation in which the hydroxy moiety is _not_ captured between a pair of
 isopropyl methyl units.  Can anyone provide me with additional, especially more
 recent, references providing experimental phenolic O -- H stretch frequencies as
 a function of phenolic conformation?
      Thanks in advance to all responders.
 With kindest regards,
 (Dr.) S. Shapiro
 Inst. f. orale Mikrobiol. u. allg. Immunol.
 Zent. f. Zahn-, Mund- u. Kieferheilkd. der Univ. ZH
 Plattenstr. 11
 Postfach
 CH-8028 ZH 7
 Internet: toukie |-at-| zui.unizh.ch
 FAX-nr: ( ... + 1) 261'56'83