PGOPHER, a program for rotational, vibrational and electronic spectra

Laser Group homepage
23 July 2014: In addition to the website, PGOPHER can now be cited via a permanent digital object identifier, doi:10.5523/bris.huflggvpcuc1zvliqed497r2.

23 April 2014: Two bugs have been found concerning simulating Stark and Zeeman effect spectra. Spectra in the presence of external fields involving symmetric tops with degenerate vibronic states included spurious extra transitions, and the M dependence of the intensity of multiphoton transitions, or ordinary transitions with random polarisation, was calculated incorrectly. These have been fixed in development versions above 8.0.186.

Version 8.0.102 (11 December 2013): Minor update to fix crashes in energy level plots in the Mac version, and some issues with vibrational calculations. See the release notes for a more detailed list of problems fixed; there are no new features

Version 8.0 (2 December 2013): A significant new release of PGOPHER, with the major new feature being the addition of the calculations involved in a Force Field Analysis to PGOPHER. This allows vibrational frequencies and many other related quantities including Franck-Condon factors and centrifugal distortion distortion constants to be calculated from a force field expressed in terms of bond bending and stretching coordinates or symmetry coordinates. Fitting the force field to any reasonable combination of observations is also possible, and this has been set up so that scaling or otherwise adapting ab initio force fields is straightforward. Other significant new features include:
  • Custom population functions, allowing an essentially arbitrary function to be used as an alternative to the Boltzmann distribution.
  • Flexible use of HITRAN and ExoMol linelists.
  • Axis switching effects
  • Custom transition moment functions to allow for Herman-Wallis factors
  • Tweaks for Mac usage, including more (Mac) standard shortcut keys and dropping of files onto main window.
  • 64 bit version now part of the standard release, allowing larger calculations to be performed.
See the release notes for a detailed list of changes, including notes on upgrading from previous versions.

5 Aug 2013: Very low temperatures (~0.01 K or less) could cause some transitions to be missed if Tspin is not the default. Versions after 7.1.459 show an error message in these circumstances.

15 Mar 2013: Incorrect values for the Einstein A coefficient can be displayed if the plot units are different from the calculation units. This is fixed in versions after 7.1.325; for older versions just make sure the plot units and calculation units are the same when A is required.

28 Jul 2011: Selected transitions are omitted for simulations of the unusual symmetric top point groups C3h...C6h (involving states with E symmetry) and S4...S12 (for non totally symmetric states). An initial fix has been made in version 7.1.217 and above.

7 Feb 2011: An issue with simulating spectra with equivalent nuclei has been discovered. It arises if either:

The issues have been fixed in version 7.1.145 and above.

13 September 2010 - Version 7.1: Bug fix release - In the vibrational only mode, linear molecule Franck-Condon factor calculations for states with non zero vibronic angular momentum had incorrect intensities, as the degeneracies were not properly accounted for. A few other minor issues have also been fixed.

15 June 2010: New Full Release (7.0): Apart from many minor improvements and bug fixes, several features have been added at the request of users:
  • Interactive adjustment of parameters with the mouse.
  • Fits to combination differences.
  • Uncertainties in calculated line positions can now be estimated from the results of least squares fitting. This is enabled by the ShowEstUnc setting at the top level.
  • A separate nuclear spin temperature can be set, Tspin, to model the non equilibration of nuclear spin states on cooling, such as the ortho and para states in H2.
  • Alternative, simplified line list format.
  • A command line version of PGOPHER is also now available, with text or Binary format output. This is particularly suitable to using PGOPHER with other programs.
  • Doppler double peak line shape, as often found in Fourier transform microwave spectroscopy which can be used in addition to the standard Gaussian, Lorentzian and Voigt line shapes.

PGOPHER is a general purpose program for simulating and fitting rotational, vibrational and electronic spectra. It represents a distillation of several programs written and used over the past decade or so within the Bristol laser group and elsewhere, but is a re-write from scratch to produce a general purpose and flexible program. PGOPHER will handle linear molecules and symmetric and asymmetric tops, including effects due to unpaired electrons and nuclear spin, with a separate mode for vibrational structure. The program can handle many sorts of transitions, including Raman, multiphoton and forbidden transitions. It can simulate multiple species and states simultaneously, including special effects such as perturbations and state dependent predissociation. Fitting can be to line positions, intensities  or band contours.

PGOPHER is designed to be easy to use; it uses a standard graphical user interface and the program is currently in use for undergraduate practicals and workshops as well as research work. It has features to make comparison with, and fitting to, spectra from various sources easy. In addition to overlaying numerical spectra it is also possible to overlay pictures from pdf files and even plate spectra to assist in checking that published constants are being used correctly.

The program is freely downloadable from this web site for Microsoft Windows, Apple Mac and Linux. The program is released as open source, and can be compiled with open source tools. For support please contact help-pgopher@bristol.ac.uk

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