Supported Methods¶
Eight calculation types over fourteen methods and ten basis sets, all dispatched through a single Calculate tab.
Calculation types¶
| Calculation type | Output |
|---|---|
| Single Point | Energy, HOMO–LUMO gap, Mulliken charges, dipole moment |
| Geometry Opt | Optimized structure with step-by-step trajectory animation; optional frozen atoms |
| Transition State | Saddle point near the input geometry (Sella; pip install "quantui[ts]"), then a frequency check that says whether it is a transition state (one imaginary frequency), a minimum, or a higher-order saddle point |
| Frequency | Vibrational frequencies, ZPVE, IR intensities, thermochemistry at any temperature and pressure, animated normal modes |
| UV-Vis (TD-DFT) | Excitation energies, oscillator strengths, UV-Vis spectrum plot |
| NMR Shielding | ^1^H and ^13^C chemical shifts vs TMS via GIAO |
| PES Scan | 1D bond/angle/dihedral scan; energy profile + per-step geometries |
| Reorganization Energy | Marcus four-point internal reorganization energy λ = λ₁ + λ₂ for hole (cation) and/or electron (anion) transfer |
Methods by family¶
| Family | Methods |
|---|---|
| Hartree–Fock | RHF (closed-shell), UHF (open-shell radicals) — baseline reference; fastest path to convergence |
| DFT | B3LYP, PBE, PBE0, M06-2X, ωB97X-D, CAM-B3LYP, M06-L, HSE06, PBE-D3 — nine functionals spanning hybrid, GGA, meta-hybrid, range-separated, and dispersion-corrected families |
| Post-HF | MP2, CCSD, CCSD(T) — Møller–Plesset (O(N^5^)) for fast post-HF; coupled cluster (O(N^6^) singles+doubles, O(N^7^) with perturbative triples) for benchmark-quality small-molecule energies |
| Implicit solvent | PCM (C-PCM) — Water, Ethanol, THF, DMSO, Acetonitrile — single checkbox. Single point, geometry optimization (solvated at every step), frequency (PCM Hessian and IR intensities; Raman is not computed in solvent) and UV-Vis TD-DFT (solvated ground state, non-equilibrium excitations using the solvent's optical dielectric n²). Reorganization energy uses gas-phase optimizations with solvated single points. NMR and PES scans are gas-phase only |
Basis sets¶
From fast iteration to higher accuracy:
STO-3G → 3-21G → 6-31G → 6-31G* → 6-31G** → cc-pVDZ → cc-pVTZ → def2-SVP → def2-TZVP → LANL2DZ
Choosing a basis
- STO-3G — fast iteration and classroom demos
- cc-pVDZ — common research default
- def2-TZVP — higher accuracy when cost allows
For transition-metal complexes, the in-app guard nudges toward def2-SVP or LANL2DZ when a metal is paired with an incompatible all-electron basis.