DParFit 3.3
DParFit performs leastsquares fits of a diatomic molecule spectroscopic data
set consisting of any combination of microwave, infrared or electronic
vibrational bands, fluorescence series, photoassociation spectroscopy
binding energies and/or input B_{v} values, involving one or more
singlet electronic states and one or more isotopomers, to parameters defining
the energy levels of each state. The levels for each electronic state may be
described by one of:

band constants G_{v}, B_{v}, D_{v}, ... etc. for each
vibrational level of each isotopomer,

generalized Dunham expansions,

neardissociation expansions (NDE), or

mixed NDE/Dunham functions (MXS), or

independent term values for each vibrationrotation level of each isotopomer.
The effect of lambda doubling or doubletsigma spin splitting is represented
either by bandtype constants for each vibrational level of each isotopomer,
or by Dunhamtype expansions in (v+1/2). Dunham, pure NDE or MXS fits
automatically incorporate normal firstorder semiclassical multiisotopomer
mass scaling, and allow for inclusion of atomicmassdependent
BornOppenheimer and firstorder JWKB breakdown corrections (collectively
called BOB corrections) for each electronic state.
The source code for DParFit 3.3 and the associated user manual University of
Waterloo Chemical Physics Research Report CP660 (2005) are distributed
free of charge. However, I would appreciate it if use of this program were
acknowledged by citation of the above report. The manual describes the
various fitting and levelenergy representation options and provides a
detailed description of the nature of the input data files and the options
invoked by various input parameter choices. It is available as a PDF file
which may be downloaded or read and printed from the above www link. The
FORTRAN source code and the sample data file used to generate the sample
outputs shown in the manual are automatically distributed (by email) to
anyone who fills in the form: Download
DParFit .
DParFit 3.3 has a number of additional capabilities beyond those of
early versions of this code. Noteworthy items new to version 3.3
include 1.(b), 1.(c) and 9.

LambdaDoubling Changes, Corrections and Extensions
(a) The isotopomer massscaling of Lambda doubling expansion in Eq.(17) in the
manual and in the code has been now utilizes the proper
inversesquare reducedmass factor associated with each power of [J(J+1)].
(b) The treatment of Lambda doubling has been generalized to treat
cases with Lambda > 1 properly, so the leading term now has the proper J and
reduced mass dependence {[J(J+1)]/mu^{2}}^{Lambda}
(c) The input of the parameters controlling the treatment of Lambda
doubling have been separated from those associated with mechanical rotation.
This has significant implications w.r.t. the structure of the input data file.
In particular: the old reads ^{#}7 & 19 are gone, and reads
^{#}9 & 21 are changed (to omit parameter NQC).

Electronic states with doubletsigma symmetry may now be treated, and the
associated spinrotation parameters may be represented in either bandconstant
or (massscaled for different isotopomers) Dunhamtype expansion format.

Absolute binding energies, such as those obtained from photoassociation
spectroscopy, may now be introduced as a distinct data type.

For any given electronic state, the fit may may be used to determine an
independent parameter (the "term value") for each distinct
vibrationrotationparity level of each isotopomer.

Vibrational energies and inertial rotational constants Bv may be represented by
the MXS "mixed" Dunham/NDE functions proposed by Tellinghuisen

Pure NDE (or MXS) expressions for Bv may now use the full range of types of
NDE functions, rather than only the exponentialNDE form.

(a) Bandconstant fits to CDC's may be combined with analytic (Dunham, etc.)
treatments of G_{v} & B_{v}, and
(b) Bandconstant fits to all mechanical rotational contants (B_{v}'s
and CDC's) may be combined with analytic (Dunham, etc.) treatments of Gv.
These extensions facilitate the treatments of modestly perturbed
states.

"Robust" leastsquares fits may now be performed: see J.K.G. Watson, J. Mol.
Spectrosc. 219, 326328 (2003), and references therein.

Parameter PRCMO input on data line ^{#}3 has been replaced by PRINP
which allows a user to print out a summary of the input data immediately
after it is read in (rarely useful). The compact [calc. obs.] fit summary
now is always printed at the end of each run, and the full [calc. obs.]
output listing is always written to Channel8.
Beginning with version 3.0, there were a number of minor modifications of and
additions to the channel5 "instruction" data file, which are outlined on the
link:
Version3 Data File Modifications
The earlier upgrade from Version 1.0 of this code incorporated a number
of enhancements, including a reorganization of the required form of the main
experimental data input file. For current users of Version 1.0, a
summary of, and partial explanation for these changes found in the link Version
2.0 Updates. This "Updates"
link also provides access to a script for converting input data files
prepared for use in Version 1.0 to the modified format expected by the
current version.
I would be pleased to receive information regarding apparent or real
malfunctions of this code, or weakness in the documentation, by post [to the
address on the manual], by voice [at (519) 8884051] or by email to the
address given below. However, the program should be fairly robust, and is
fairly extensively commented internally. If you encounter problems obtaining
a copy of the manual from the www, a postscript (or if necessary, paper) copy
may be obtained by sending me a note by email.
Site owned by R.J. Le Roy: leroy @ UWaterloo.ca
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