A test of the r_{m} method of structure determination
Abstract
The r_{m} method of determining molecular structures from isotopic zeropoint rotational constants is tested by applying it to synthetic data for OCS calculated from an assumed equilibrium structure and force field. The results show that the r_{m} structure is significantly different from the r_{e} structure, unless the substitution coordinates used in the r_{m} calculation are corrected for the use of finite changes of mass ∆ m_{i} by extrapolation to ∆ m_{i} = 0. The latter procedure is not usually feasible experimentally. In the ordinary r_{m} method the errors are generally comparable in magnitude to those in Costain's r_{g} method. An exception arises when the number of structural parameters equals the number of independent moments of inertia of a single isotope (e.g., a diatomic molecule or a symmetrical XY _{2} molecule), in which case the r_{m} structure is in good agreement wich the r_{e} structure.
 Publication:

Journal of Molecular Spectroscopy
 Pub Date:
 January 1978
 DOI:
 10.1016/00222852(78)900267
 Bibcode:
 1978JMoSp..69...47S