From 1985 to 1994, the SPECTRO program was developed in Cambridge by Jeff Gaw and coworkers in the group of Nicholas Handy. Since then, the program has been widely used to facilitate the spectroscopic analysis and characterization of many molecular systems in the atmospheric sciences and astronomical studies.  Using a reliably determined geometry and quartic force field (QFF) of any molecule, the SPECTRO package can carry out a 2nd-order Perturbation Theory analysis in normal coordinates to compute various spectroscopic constants, including rotational constants, quartic and sextic centrifugal distortion constants, and rotational-vibrational interaction constants, etc.  Going beyond the standard anharmonic analysis, i.e., obtaining the anharmonic constants and vibrational fundamentals, SPECTRO can also handle Fermi Resonances and Coriolis couplings.  In addition, SPECTRO can also compute vibrationally averaged bond lengths and bond angles, vibrational band intensities, and rovibrational energy levels.  With the rapid evolution of computing power and accurate ab initio methods becoming more affordable, the predictive accuracy for the spectroscopic constants of many molecular species has been significantly improved.  Compared to more sophisticated variational approaches, the SPECTRO program (via 2nd-order perturbation theory) can quickly generate many directly measurable or experimentally derived quantities.  This capability may play a very important role in the coming era of high-resolution astronomical data analysis for missions such as HERSCHEL, SOFIA, ALMA, and JWST.  In this talk, we are going to give a simple historical review for SPECTRO and summarize recent applications for molecules of interest to astronomers and astrochemists.

History of a theoretical spectroscopy package SPECTRO and its recent applications in astrophysical studies

248th National Meeting (2014)

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