Unit conversion

IOData always represents all quantities in atomic units and unit conversion constants are defined in iodata.utils. Conversion to atomic units is done by multiplication with a unit constant. This convention can be easily remembered with the following examples:

• When you say “this bond length is 1.5 Å”, the IOData equivalent is bond_length = 1.5 * angstrom.

• The conversion from atomic units is similar to axes labels in old papers. For example. a bond length in angstrom is printed as “Bond length / Å”. Expressing this with IOData’s conventions gives print("Bond length in Angstrom:", bond_length / angstrom)