Reference data are defined in normal MOPAC data sets. Each dataset describes a single system, such as cesium in the 2P state, (an excited state), water (a molecule), NO (a radical), sodium sulfate anion, [NaSO4]-, an anion, etc. The values of all reference data, except geometric, are given on Line 3 of a MOPAC data set. For geometric reference data, the reference values (bond lengths and angles) are given in the Z-matrix.
Text on Line 3 is not used by MOPAC, but is used by PARAM.
| <> | A geometric parameter is not to be used as a reference |
| <text> | A geometric parameter is to be used as a reference |
| D=n.nn | The reference dipole moment is defined as n.nn |
| DR=<text> | The reference dipole source is given by the mnemonic <text> |
| DWT=n.n | The default reference dipole moment weight is to be multiplied by n.n |
| GR=<text> | The reference geometry source is given by the mnemonic <text> |
| GWT=n.n | The default reference geometry weight is to be multiplied by n.n |
| H=n.nn | The reference Heat of Formation is defined as n.nn |
| H=n.nn+<text> | The reference Heat of Formation is defined as n.nn relative to ,text> |
| HR=<text> | The reference Heat of Formation source is given by the mnemonic <text> |
| HWT=n.n | The default reference Heat of Formation weight is to be multiplied by n.n |
| I=n.nn | The reference Ionization Potential is defined as n.nn |
| IR=<text> | The reference Ionization Potential source is given by the mnemonic <text> |
| IWT=n.n | The default reference Ionization Potential weight is to be multiplied by n.n |
| ROOT=<text> |
A named electronic state is to be used |