What is ComSpec3D ?

ComSpec3D is an online service for the calculation and visualization of Infrared and Raman spectra and corresponding normal modes.
ComSpec3D stands for Computed Spectral Data 3D-Visualization.
The service will visualize IR/Raman spectra and 3D animated VRML scenes of normal vibrations of any reasonable structure you input. All data related to the IR and raman spectra like frequencies and normal modes are based on quantum-mechanical calculations performed with the semi-empircal programm VAMP (PM3 method).
Because intensity peaks calculated by semi-empirical calculations are represented at to high wavenumbers, we have added a corection factor of 0.98 in this service. Although we have added this scoring factor, C=O bonds still are occurring at to high wavenumbers. Therefore, we have added another scoring factor (0.9) within the wavenumber range between 2100 and 1900 cm -1 to address this problem.

There are two steps in this procedure. After calculating the spectral data the first display shows a GIF of the IR and Raman spectra (Figure 1) and also a table of the important wavenumbers and IR/Raman intensities.

Step 1
Figure 1

After clicking on a wavenumber the vibration display will open. It shows an animated VRML scene of the corresponding normal mode (Figure 2).

  Step 2 Step 2 Step 2  
  Step 2  

Figure 2

System Requirements

Netscape 4.0 or higher or MS Internet Explorer 4.0 or higher, VRML 2.0 plugin; e.g. Octaga



For the input of chemical structures the service uses the JME Molecular Editor by Peter Ertl (Novartis).


The spectral data are computed by the the semi-empiric program VAMP (Tim Clark, University of Erlangen) with the AM1 Hamiltonian.

This service was developed within the framework of the ChemVis research project. ChemVis

Usage conditions

You can use the animations generated by this service free of charge for every purpose you can imagine. If you put them on a Web site, the HTML document embedding the VRML file must contain a link to this page. A small footnote is sufficient. After some bad experiences with other free data we provided to the Internet community, you are explicitly forbidden to include these scenes in any CD or other medium you charge for without prior contact and an agreement in writing.
We will treat the structures confidentially, but they travel unencrypted on the Internet, and we log them to evaluate program performance.