A NEW WAY OF ANALYZING VIBRATIONAL-SPECTRA - IV - APPLICATION AND TESTING OF ADIABATIC MODES WITHIN THE CONCEPT OF THE CHARACTERIZATION OF NORMAL-MODES
Z. Konkoli et al., A NEW WAY OF ANALYZING VIBRATIONAL-SPECTRA - IV - APPLICATION AND TESTING OF ADIABATIC MODES WITHIN THE CONCEPT OF THE CHARACTERIZATION OF NORMAL-MODES, International journal of quantum chemistry, 67(1), 1998, pp. 41-55
The CNM (characterization of normal modes) method for extracting chemi
cal information out of vibrational spectra is tested for vibrational s
pectra of molecules with relatively strong or relatively weak coupling
between internal vibrational modes. Symmetry, parameter set stability
, and frequency uncertainty tests are applied to check whether interna
l vibrational modes. internal mode frequencies, and amplitudes A(n mu)
comply with symmetry, are independent of the set of internal paramete
rs zeta(n) used to describe molecular geometry or fulfill a Lorentzian
correlation between amplitudes A(n mu) and frequency differences Delt
a omega(n mu) = omega(n) - omega(mu). In all cases considered, amplitu
des A(n mu) based on adiabatic internal modes and mass or force consta
nt matrices as metric Omicron are superior to any other definition of
amplitude. They represent the basic elements of the new CNM method tha
t leads to chemically reasonable results and presents a new way of ext
racting chemical information oat of vibrational spectra. A number of d
eficiencies of the potential energy distribution (FED) analysis is dis
cussed. (C) 1998 John Wiley & Sons, Inc. Int J.