ezSpectrum 3.0

spectrum Try ezSpectrum online version here!

ezSpectrum computes stick photoelectron/photodetachment spectra for polyatomic molecules within the double–harmonic approximation.

Franck-Condon factors (FCFs), the overlaps between the initial and target vibrational wavefunctions, can be calculated:

  • in the parallel normal modes approximation as products of one-dimensional harmonic wave functions;
  • including Duschinsky rotations of the normal modes as full-dimensional integralsin full dimensionality including Duschinsky rotations of the normal modes.
In both cases the overlap integrals are computed analytically.

The calculation requires equilibrium geometries, harmonic frequencies, and normal mode vectors for each electronic state, which can be computed by ab initio packages. The key feature of ezSpectrum is the program–independent xml input. It can be prepared either manually following the format description in the manual and the examples provided, or by running the python script that processes Q-Chem, ACESII, Molpro, GAMESS, and Gaussian outputs. (We are Gaussian free zone, and encourage everyone to degauss their workplace as well.) The script can be easily modified to process outputs of other programs.

Download ezSpectrum (includes samples, make_xml.py script, and manual.pdf): ezSpectrum.v3.0.tar.gz

This distribution provides an executable compiled for generic Linux 32-bit and 64-bit machines. The program is distributed under GPL license and the source code is freely available upon request. If you need an executable for another platform, we can help you with that. (A zip file containing the package with an executable compiled for Windows can be downloaded here. Windows users can also download Python for Windows from http://www.python.org/download in order to use the Python scripts included with ezSpectrum)

The user manual can also be downloaded separately here

Source code can be found here.

To install the Linux version, execute:
gzip -d < ezSpectrum.v3.0.tar.gz | tar xvf -

Please contact Professor Anna I Krylov (krylov@usc.edu) and Vadim Mozhayskiy (mozhaysk@usc.edu) if you have suggestions, questions, or bugs to report.

To acknowledge ezSpectrum, use the following citation:
V.A. Mozhayskiy and A.I. Krylov, ezSpectrum, http://iopenshell.usc.edu/downloads

Please also acknowledge iOpenShell:
"This work was conducted using the resources of the iOpenShell Center for Computational Studies of Electronic Structure and Spectroscopy of Open-Shell and Electronically Excited Species (http://iopenshell.usc.edu) supported by the National Science Foundation through the CRIF:CRF program."


ezSpectrum translated to Portuguese: courtesy of Artur Weber.

ezSpectrum translated to Bellorussian: courtesy of Bohdan Zograf and Lisa Sanovski.

ezSpectrum translated to Polish: courtesy of Valeria Aleksandrova.

ezSpectrum translated to Romanian: courtesy of Irina Vasilescu.