PETRA - Parameter Estimation for the Treatment of Reactivity Applications


PETRA is a program package comprising various empirical methods for the calculation of physicochemical properties in organic molecules. All methods are empirical in nature and have been developed over the last 20 years in the research group of Prof. Dr. J.Gasteiger.

The following chemical effects can be quantified:

  • heats of formation
  • bond dissociation energies
  • sigma charge distribution
  • pi charge distribution
  • inductive effect
  • resonance effect and delocalization energies
  • polarizability effect


PETRA has shown to be applicable in the following fields

  • pharmaceutical lead discovery and lead optimization
  • definition of similarity and diversity of combinatorial libraries
  • quantitative structure activity and property relationships (QSAR and QSPR)
  • spectra prediction and structure elucidation
  • prediction of chemical reactivity

Online Access

A free online service for calculating various physicochemical properties is available. You can read a short introduction or go directly to the input form. It is possible to run the calculations for a molecule drawn by an interactive molecule editor.


The manual is available in HTML or PDF format.


PETRA is available for various Unix derivatives:

  • IRIX5.3 to 6.5
  • SunOS5.6 and lower
  • HP-UX10.10
  • Linux (Kernel2.2/2.4/glibc2 and higher)


J. Gasteiger,
Empirical Methods for the Calculation of Physicochemical Data of Organic Compounds,
in: "Physical Property Prediction in Organic Chemistry",
Ed. C. Jochum, M. G. Hicks, J. Sunkel,
Springer Verlag, Heidelberg, 119-138, 1988.

See a comprehensive list of publications about the calculation of electronic effects and physicochemical data in organic compounds.


For scientific questions and/or discussions concerning PETRA please contact Prof. Dr. Johann Gasteiger or Dr. Thomas Kleinöder

If you want to evaluate or purchase an inhouse version of PETRA or use the data commerially please contact Molecular Networks GmbH.