Tutorial¶
These tutorials double as a course in computational quantum chemistry. If you are new to vibe-qc or to the field, start with the Introduction for the background, the molecular/periodic split, and the learning path; otherwise work down from wherever you like. Each page is a complete worked example you can paste straight into a Python interpreter.
For downloadable inputs, full logs, QVF archives, and vibe-view captures, see reference outputs and the full example-output catalog. The catalog includes the curated chi-CCM-B periodic QVF validation fixtures for checking finite-BvK cells, torus-aligned grids, and Wannier-centre overlays.
Molecular: foundations
Molecular: properties & workflows
- Post-SCF properties: charges, bonds, dipole
- Orbital and density visualization
- Geometry optimization
- Vibrational frequencies
- Thermodynamics at temperature
- Molecular dynamics (NVE, NVT, NPT)
- Nudged elastic band: reaction paths and transition states
- Relaxed potential-energy surface scans
- Solvation in water (CPCM)
Molecular: methods & accuracy
- Basis-set convergence
- Pt cluster with LANL2DZ: heavy-element ECPs
- DFT functional comparison
- Dispersion corrections (D3-BJ)
- Double hybrid: B2PLYP step by step
- Range-separated hybrids: ωB97X and the HOMO ≈ −IP property
- Modern functionals: VV10 and the ωB97X-V / ωB97M-V wave
- RIJCOSX SCF and analytic gradients on glycine
- Stiff molecular SCF: rescuing oscillation with EDIIS+DIIS
- Letting DIIS choose its own depth: R-CDIIS and AD-CDIIS
- Second-order SCF: Newton, SOSCF, and TRAH
- Excited states with TDDFT
Molecular: correlation & fast methods
- Natural orbitals and the idempotency diagnostic
- Verifying an RI-MP2 auxiliary basis
- Canonical CCSD(T): the gold-standard reference
- Local correlation with DLPNO
- Non-mean-field solvers: Selected-CI, DMRG, v2RDM, and transcorrelated methods
- Multireference: CASSCF, CASPT2, NEVPT2
- MSINDO: semiempirical INDO
- Semiempirical DFTB: fast preoptimization
- More semiempirical methods: PM6 and GFN2-xTB
- Machine-learning interatomic potentials with MACE
Periodic: foundations
Periodic: the cyclic cluster model
Periodic: methods
Periodic: electronic structure
- Band structure and density of states
- LiH at multiple k-points: KRHF vs Peintinger 2013
- Projected density of states (PDOS)
- Smearing for metals: Fermi-Dirac, Methfessel-Paxton, and cold smearing
- The Gilat-Raubenheimer net: metallic Brillouin-zone integration
- DFT+U for correlated transition-metal oxides
Periodic: basis & real systems
Periodic: phenomena, convergence & visualization
- Peierls dimerisation of a 1D H-chain
- Open-shell Mg⁺• in a periodic box: UHF GDF with Makov-Payne
- Periodic orbital cubes and XSF files
- Tight-cell DFT with the periodic Becke partition
- Periodic SCF convergence: damping, DIIS, and level shifts
- Symmetry-aware storage of lattice integrals (SYM3a)
- XSF and BXSF: periodic volumetric visualisation
Operations
- Running in parallel
- Submitting a job to a remote machine with
vq - Fetching external data with
vqfetch - Reproducing an example output
- The QVF file format, end to end
- Adopting QVF: how to implement a writer in your own code
- Auto-citations: from
.outto manuscript bibliography - Viewing geometries, orbitals, and vibrations with MolTUI
- vibe-view: an end-to-end walkthrough
- Working with vibe-view
- Cross-validating against ORCA, Psi4, and PySCF
New to vibe-qc or to the field? The Introduction lays out the background, the molecular and periodic tracks, and how to run these examples. The molecular tutorials use the built-in basis sets (STO-3G, 6-31G*, cc-pVDZ) that ship with vibe-qc; the periodic tutorials use the pob-* basis sets designed to avoid linear dependence in crystals.