Prepare, read and analyse quantum‑chemistry calculations

Method, basis set, keywords and sections are copied into the input as written. Functionals that already include dispersion (such as wB97XD) need “None”.

Bands are broadened in energy whatever the x axis. Add an experimental spectrum (two columns, x in the plot’s unit) to the chosen files to overlay it.

A scaling factor is applied only if you choose one; take it from the literature for your method and basis set. Add an experimental spectrum (two columns, cm⁻¹) to the chosen files to overlay it; an IR spectrum in transmittance is converted to absorbance.

Grid spacings follow Multiwfn’s cube presets; finer grids give smoother surfaces but take longer. The isovalue changes the drawing only, without recomputing. The list also offers the total electron density and, for open shells, the spin density (blue where α electrons dominate); their isovalue is in e/bohr³.

Hirshfeld weights use Multiwfn’s built-in free-atom densities. To use your own free atoms instead, as ORCA and Q-Chem do, add one neutral single-atom wavefunction file per element (same method and basis set) with the molecule’s file; each atom is spherically averaged. The standard grid is accurate to about 5 × 10⁻⁵ e; the fine grid takes about three times longer.

The cube grid only affects the isosurfaces and cube files. The integration grid is used for Sr and the atom contributions; on the test molecule the standard grid reproduces the exact hole and electron integrals to 10⁻⁴.

Each orbital counts once and is broadened to unit area, so the curve is in orbitals per eV. The default window is −0.8 to 0.2 Eh (−21.77 to 5.44 eV), as in Multiwfn. Overlap DOS is positive where the two groups bond and negative where they are antibonding.