: a program for Hirshfeld surface analysis, visualization and quantitative analysis of molecular crystals.

is a native cross-platform program supported on Windows, MacOS and Linux with the primary function of visualization and investigation of molecular crystal structures, especially through the decorated Hirshfeld surface and its corresponding two-dimensional fingerprint, and through the visualization of void spaces in the crystal via isosurfaces of the promolecule electron density. Over the past decade, significant changes and enhancements have been incorporated into the program, such as the capacity to accurately and quickly calculate and visualize quantitative intermolecular interactions and, perhaps most importantly, the ability to interface with the and programs to calculate quantum-mechanical properties of molecules. The current version, , incorporates these and other changes, and the software can be downloaded and used free of charge for academic research.

Wave functions derived from experiment. V. Investigation of electron densities, electrostatic potentials, and electron localization functions for noncentrosymmetric crystals.

The constrained Hartree-Fock method using experimental X-ray diffraction data is extended and applied to the case of noncentrosymmetric molecular crystals. A new way to estimate the errors in derived properties as a derivative with respect to added Gaussian noise is also described. Three molecular crystals are examined: ammonia [NH(3)], urea [CO(NH(2))(2)], and alloxan [(CO)(4)(NH)(2)].

Wavefunctions derived from experiment. IV. Investigation of the crystal environment of ammonia.

Constrained Hartree-Fock calculations have been performed to obtain wavefunctions that reproduce experimental X-ray structure-factor magnitudes for crystalline NH3 to within the limits of experimental error. Different model densities using both a single molecule and clusters of NH3 in the calculation of X-ray structure-factor magnitudes have been examined. The effects of the crystalline lattice on the experimental wavefunction of the NH3 unit can be reproducibly recovered.

Wavefunctions derived from experiment. III. Topological analysis of crystal fragments.

A constrained wavefunction model has been used to extract a Hartree-Fock wavefunction for C2H2O4.4H2O from both low-angle (sin theta /lambda < 0.71 A-1, 571 reflections) and full (sin theta / lambda < 1.