TOPOND a program for the topological analysis of the electron density (C. Gatti)

An update version of the TOPOND program is currently available.

Release notes

Being fully incorporated into CRYSTAL23, TOPOND23 enjoys further advantages such as:
  • a complete parallelization of the main algorithms with the possibility of studying even larger and more complex systems,
  • the extension of the set of bases to the use of f and g type functions for the computation of electron density and its derivatives, up to the fourth order and
  • the availability of graphical tools based on Python for an accurate and flexible 2D-visualization of all calculated properties

About the Program

The program allows for the complete and detailed topological analysis of the Electron Density, ρ, and its derivatives up to the fourth order, primarily consisting of:
  • search of the critical points of the density, ∇ ρ = 0, and of the Laplacian, ∇3 ρ =0;
  • analysis of critical points (kind of critical point, bond order, energy density, virial theorem, etc.);
  • search for the atomic basins and integration of atomic properties within them: charge, kinetic energy, virial density, Becke localization function, Shannon entropy, etc..

Electron Density of the Urea bulk Electron density difference of the Urea bulk
Laplacian (∇2 ρ) and its Critical Points; Atomic basins and local and integrated quantities, such as kinetic energy, virial density, Becke localization function, charge density, ...


A bit of history

The original TOPOND suite of programs was developed by Carlo Gatti (ISTM - CNR, Milano (Italy)) to perform the topological analysis of the Electron Density, according to the Quantum Theory of Atoms in Molecules as developed by Bader (QTAIM).
Carlo Gatti proposed an extension of the method for the study of atoms in crystals and with this aim he implemented the first version of the code TOPOND98.
Since CRYSTAL14, the code has been incorporated into CRYSTAL and it is accessible by specifying the keyword TOPO in the "properties" module (see the CRYSTAL17 User's Manual for details).
While retaining all the functionalities of TOPOND98, this TOPO section of CRYSTAL enables the user to perform a topological analysis of the periodic electron density directly in CRYSTAL, thereby avoiding the use of an interface between CRYSTAL and TOPOND and the creation of external files with information from CRYSTAL.
On top of this, there is no longer the need to resize the code as a function of the dimension of the investigated system since all variables are dynamically allocated as in other parts of the CRYSTAL code.



The following documentation is available: