A numerical method for the simultaneous determination of term values and molecular constants
Review articleOpen access
Nils Åslund - No affiliation found
1974/03/30 Full-length article DOI: 10.1016/0022-2852(74)90245-8
Journal: Journal of Molecular Spectroscopy
AbstractA method is presented for the simulatneous determination of term values and molecular constants. The method is an extension of an earlier method, the so-called term value approach, for determining such constants. Whereas the latter is a two step procedure, the new method is a one step procedure. In this way a simplifying assumption inherent in the original term value approach (that, in the second step, the term values are regarded as independent measurements) is circumvented.Further the new method avoids some difficulties that may arise when the former approach is applied to systems where the term values form disconnecting sets. All the features of the original term value approach are preserved, including the one that also very large systems can be dealt with on computers of moderate size.Some comparative tests performed with the new method indicate that, in certain cases, the above approximation has a significant effect on the error estimates of the unknown molecular constants. This confirms observations reported previously by Albritton et al. J. Mol. Spectrosc. 46, 67 (1973). On the other hand, observations made by the same authors that also the values of the molecular constants may be significantly affected are not confirmed. It is found that the reported differences are explained by other causes than the removal of the above assumption.It is emphasized that the error estimates obtained with the new method may still be inadequate. Another simplifying assumption, that the line measurements have equal weights, remains to be removed. This objection applies to other methods as well. Reference is made to work in progress to cope with this problem by means of new measuring techniques.
Request full text