PGOPHER

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.

Version 7.1 (13 September 2010): 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.

New in version 7.0 (15 June 2010): 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 for 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.
  

New in the previous version (6.0):

• A mode for simulating vibrational structure, including anharmonic and Renner-Teller effects, starting from a harmonic model. The intensity calculation includes full multidimensional Franck-Condon factors taking account of both mode displacements and mixing between modes (The Dushinsky effect).
• Spectra in the presence of static external electric and/or magnetic fields can now be simulated, including plots of energy levels against electric field suitable for predicting Stark deceleration, focusing and trapping of molecules.

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.

Graphical User Interface Features

• Simple enough to use for undergraduate practicals, but flexible enough to use for multiple interacting states.
  
• Multiple simulations coloured by species, isotope, state or transition type.
  
• Interactively changing spectrum range, temperature, linewidth, display style.
• Displaying Fortrat diagrams and energy level plots
• Select transitions by lower or upper state J, symmetry or ΔJ.
• Right clicking on peaks to see assignment.
• Overlaying experimental spectra from file(s) or the clipboard (frequency, intensity format).
• Overlay pictures from pdf files or other sources.
  
• Alt+left mouse dragging experimental spectra to adjust offset between simulation and overlay.
• Built in Calibration (I₂, Ne, Fe) for experimental spectra.
• Energy Level plots.
  

Calculation Features

• Linear molecules in Hund's case (a) or (b). (Other cases can be handled with some restrictions.)
  
• Symmetric top molecules
• Asymmetric top molecules
• A separate mode for simulating Vibrational structure only, based on a harmonic model, but anharmonic and Renner-Teller effects can be added. The intensity calculation includes full multidimensional Franck-Condon factors including both mode displacements and mixing between modes (The Dushinsky effect).
• Spectra in the presence of static external electric and/or magnetic fields can be simulated, including plots of energy level against electric field suitable for predicting Stark deceleration, focusing and trapping of molecules
• Open and closed shell systems (symmetric tops are currently closed shell only)
  
• Simulates microwave, infra-red and electronic absorption and emission spectra.
• Multiphoton and Raman transitions, with any combination of transition moments including interfering transition moments.
  
• Handling an arbitrary number of states and perturbations between them.
• Fitting to line positions,  band contours or line intensities.
• Flexible input formats, including HITRAN (http://www.hitran.com) .par files and JPL (http://spec.jpl.nasa.gov/) .cat files.
• Many molecular parameter (.par) data files for Herb Pickett's CALPGM spectroscopy program suite (http://spec.jpl.nasa.gov/) can be imported as PGOPHER input files.
  
• Handling arbitrary combinations of isotopes and molecules with spectra coloured for easy identification.
• Simulate effects of quantum number dependent predissociation on line width and intensity.
• Hyperfine structure (not currently for symmetric tops).
• Symbolic matrix elements available for linear molecules and asymmetric tops. (Right click on a state or constant and select Matrix Elements)
• For larger calculations, parallel calculations can be done on systems with multiple CPU's.
  

Supported Platforms

• Windows
  
• Linux
  
• Apple Mac