Glossary¶
- QM/MM¶
Quantum mechanics/molecular mechanics. q2m3 treats a small QM region with PySCF and PennyLane while representing the solvent environment with classical point charges and MM force-field terms.
- QPE¶
Quantum phase estimation. q2m3 uses QPE circuits to estimate molecular energies from a time-evolution phase.
- EFTQC¶
Early fault-tolerant quantum computer. In q2m3, this term is used for resource-estimation studies such as logical qubit and Toffoli counts.
- RDM¶
Reduced density matrix. The 1-RDM is used for Mulliken population analysis and quantum-to-classical observable transfer.
- active space¶
The selected electrons and orbitals included in a quantum calculation. q2m3 documents active spaces as electrons/orbitals and the resulting system qubit count.
- Trotterization¶
Approximation of Hamiltonian time evolution by decomposing it into products of simpler exponentials. Trotter depth affects QPE accuracy and Catalyst compile size.
- delta_corr-pol¶
Correlation-polarization coupling: the change in electronic correlation energy caused by the MM environment.
- Catalyst¶
The PennyLane compilation stack used for
@qjitworkflows. q2m3 uses it where compile-once/reuse-many execution is intended.- IR cache¶
A cache of Catalyst intermediate representation artifacts used to avoid repeating expensive compilation stages for unchanged circuit structure.
- Hartree¶
Internal energy unit used by q2m3.
- kcal/mol¶
Reporting unit used only after explicit conversion from Hartree.
- Hamiltonian 1-norm¶
Sum-of-coefficients measure used by the EFTQC resource-estimation path.
- MM embedding¶
Electrostatic coupling of classical point charges into the QM Hamiltonian.
- phase wrapping¶
Ambiguity caused when the energy phase exceeds the finite QPE register range and wraps modulo one.