| Acronym | Meaning |
| IVAP | Intimate Valence Alternation Pairs (bonding Model In Electronic Structure Calcns.) |
| MSO | Molecular Spin Orbital |
| FGRM | Fourier-grid R-matrix Formalism (in Scattering Problems) |
| MIDI-N | Split-type Contracted GTO Basis Set (n = 1 |
| CCI | Crevice Corrosion Index |
| CTPGF | Closed Time Path Green Function (in Many-body Theory) |
| RECP | Relativistic Effective-core Potential |
| NSWS | National Surface Water Survey |
| DBTT | Ductile-to-brittle Transition Temperature |
| UKIRT | United Kingdom Infrared Telescope |