| Acronym | Meaning |
| PSEP | Polyhedral Skeletal Electron Pair (for Metal Clusters) |
| DHS | Department Of Homeland Securitypar |
| ERD | Emergency Response Division |
| DPCILO | Differential Perturbative Configuration Interaction Using Localized Orbitals |
| OHMS | Office Of Hazardous Materials Safety |
| PPA | Pollution Prevention Act (of 1990) |
| TGEP | Trace Gas Exchange Program |
| VCDT | Vienna Canyon Diablo Troilite |
| FP | Fluorescence Polarizationpar |
| LDPEX | Cross-linked |