Interactive ground state fitting program for symmetric tops

        SYMF is adapted from the S-reduction part of ASFIT, and fits prolate type constants.  The constant sequences necessary to fit h3 doubling in C3v tops, or d2 doubling in C4v tops are available.  Although such issues can be dealt with using simple closed formulae there are specific peculiarities in the behaviour of energy levels which come in near the spherical limit. Diagonalisation of the Hamiltonian becomes mandatory, as described in connection with the MMW spectrum of trichloroacetonitrile, for the analysis of which this program was developed:

        G.Cazzoli and Z.Kisiel, J.Mol.Spectrosc. 159, 96-102 (1993)

        The program can of course also be used even when only the diagonal constants are necessary, although all asymmetric top constants up to decadic can be specified. It is up to the user to set only those constants which are reasonable for his molecule.  Some useful features:

  • most interactive features and cyclic operation as inherited from ASFIT, but note that several on-line modifications of transitions are not available - these have to be made with an external editor
  • central, intensity weighted frequencies of unresolved pileups for lowest K-values can be fitted
  • since calculation is in full diagonalization it is possible to use only one of the two components of a splitting pair (such as for K=3 doubling in a C3v top)
  • if K=3 (or similar) doubling is not resolved but is suspected of broadening the observed lines then the mean frequency of the two components can be fitted
  • current limit on J is 250
  • new user friendly data file format available from Feb 2001
  • annotations can be placed between transition declarations, either as alphanumeric comments, or just spacing lines

SYMF.FOR The listing, the extension .SMF is reserved for the data
TCAC.SMF The data for trichloroacetonitrile.
  • The number of transitions can be set to some larger value and the program will then count the number of transitions that were actually found
  • The number of constants is the number of leading constants in the Hamiltonian that follow (counting also the empty line after B)
TCAC.RES Results for the above - note that near-sphericity makes frequencies sensitive to the value of the axial rotational constant A

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SYMmetric TOP ground state predictive program

        This is a simple predictive program for ground state, symmetric top transitions, from constants up to sextic.   The idea of the program was to print out compact predictions for the heavier symmetric tops which would be handy during mm-wave measurements. 

        A useful feature of SYMTOP is that it calculates uncertainties in the predicted transitions from both uncertainties in the individual constants and (if available) the correlation matrix - check the difference...

SYMTOP.FOR The listing, the extension .SMT is reserved for the data
TBNC.SMT The data for tertiary butyl isocyanide. The input has been modified for consistency with what I attempt to preach on this web site - namely that it should be as self-documenting as possible.
TBNC.RES The results for the data above, can be compared with J.Mol.Spectrosc. 151, 396 (1992)

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Fitting of v=1, E-state transitions in a C3v symmetric top

        LFITD uses the full diagonalization approach although the complete 2(2J+1) energy matrix is first factorized into an A-symmetry block and two degenerate E-symmetry blocks, each ca. 3J/2 in size. The method is well described in K.M.T.Yamada, M.Bester, M.Tanimoto, G.Winnewisser, J.Mol.Spectrosc. 126, 118 (1987).  The J substate labeling is in terms of Kl-1.  The program is related in many ways to ASFIT and SYMF, so that the mode of operation, internal structure and output are similar.

LFITD.FOR The listing, the extension .LFD is reserved for the data
CYANPROP.LFD The data for cyanopropyne, v12=1 from Yamada et. al. J.Mol.Spectrosc. 126, 118 (1987).
CYANPROP.RES Output for the above
SID3FV6.LFD The MMW data for SiD3F, v6=1: note the t-type splitting doublets and the use of exclusions to predict components
SID3FV6.RES Output for the above: can be compared with the final results in J.Mol.Spectrosc. 197, 85 (1999).

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Fitting of v=2, E-state transitions in a C3v symmetric top

        V2E is a modification of the program diag3v written by J.Demaison and used for CD3CN. The approach is to fit the vl = 20 and 2-2 states simultaneously by using the additional  l dependent terms Xll and B3 - see J.Cosleou, G.Wlodarczak, J.Burie, J.Demaison, J.Mol.Spectrosc. 137, 47 (1989).  The quantisation is J, K, l, where K and l are signed quantities.  The program will also work for the v=1 state, since all the necessary constants are already there.

        The program embodies various useful statistical tests that have so far seen relatively little application in rotational spectroscopy - for explanation see J.Demaison, J.Cosleou, R.Bocquet, A.G.Lesarri, J.Mol.Spectrosc. 167, 400-418 (1994).

V2E.FOR The listing, the data is expected to be in file V2E.INP and the output is written to file V2E.OUT
CD3CN.INP Partial data set for CD3CN, v8=2: only the J=12 frequencies from J.Mol.Spectrosc. 137, 47 (1989) are put in
CD3CN.OUT Output for the above, with prediction of unreported frequencies for this J

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