DensToolKit2: A comprehensive open-source package for analyzing the electron density and its derivative scalar and vector fields

In this article, we provide details of the suite DensToolKit-v2, which consists of a set of cross-platform, optionally parallelized programs for analyzing the molecular electron density (ρ), as well as different fields and chemical indices derived from it. Notably, with this version, the user can compute the Non-Covalent Interaction index, the Density Overlap Regions Index, and fields related to single-spin-type molecular orbitals, such as the spin density. In addition, DensToolKit-v2 includes several programs for analyzing other less-known fields, such as the Density Matrix of order 1, the two-electron pair density function, and the Fourier transforms of these fields, that is, functionals in momentum space. A new sub-program to compute integrated properties of each of the fields released in the suite is included. A simple graphical user interface is released, which eases the visualization of ρ critical points topology. Most interestingly, this version includes a program that renders estimations of pKa’s of carboxylic acids and pKb’s of amines (primary, secondary, and tertiary) through refined relations between experimental data and the molecular electrostatic potential computed at isosurfaces of ρ. Details related to the speed of the programs and a few examples of how to use the program in workflows are discussed, and the source code is released through a git repository under the GPLv3 terms.