Tutorial

Start here if you’ve just installed vibe-qc and want to run something. Each page is a complete worked example — you can copy the code block straight into a Python interpreter.

Fundamentals

• Molecular Hartree-Fock
• Molecular DFT (RKS)
• Open-shell systems (UHF, UKS, UMP2)
• Initial guesses — hands-on walkthrough
• Non-mean-field solvers — Selected-CI, DMRG, v2RDM, and transcorrelated methods

Molecular properties & workflows

• Semiempirical DFTB — fast preoptimization
• Post-SCF properties: charges, bonds, dipole
• Geometry optimization
• Vibrational frequencies
• Thermodynamics at temperature
• Orbital and density visualization
• Basis-set convergence
• Dispersion corrections (D3-BJ)
• DFT functional comparison
• Range-separated hybrids: ωB97X and the HOMO ≈ −IP property
• Nudged Elastic Band: reaction paths & transition states
• Natural orbitals and the idempotency diagnostic
• RIJCOSX SCF + analytic gradient on glycine
• Pt cluster with LANL2DZ — heavy-element ECP
• Double hybrid: B2PLYP step by step
• Verifying an RI-MP2 auxiliary basis
• Solvation in water (CPCM)
• Stiff molecular SCF: rescuing oscillation with EDIIS+DIIS

Solids

• Periodic HF on a 1D H chain
• Periodic KS-DFT
• Madelung constants via Ewald summation
• Band structure and density of states
• Why solid-state calculations use pob-TZVP
• Peierls dimerisation of a 1D H-chain
• Projected density of states (PDOS)
• 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)
• Solid-state walkthrough: LiH rocksalt with pob-TZVP
• Tutorial 30: H-chain BvK equivalence — vibe-qc’s CCM ancestor
• 33. MgO from Materials Project — vqfetch end-to-end
• 34. LiH at multi-k — KRHF targeting Peintinger 2013 SI Table 2
• 35. Open-shell Mg⁺• in a periodic box — UHF GDF + Makov-Payne
• Fermi-Dirac smearing for metals and small-gap solids
• 43 — XSF and BXSF: periodic volumetric visualisation

Operations

• Running in parallel
• Tutorial 26: Cross-validating against ORCA, Psi4, PySCF
• Tutorial 27: Viewing geometries, orbitals, and vibrations with MolTUI
• Tutorial 29: Reproducing a reference output
• Auto-citations: from .out to manuscript bibliography
• Tutorial 45: vibe-view end-to-end walkthrough
• Tutorial 47: The QVF file format, end to end
• Submitting a job to a remote machine with vq

The molecular tutorials use libint’s built-in basis sets (6-31G*, cc-pVDZ, STO-3G) that ship with vibe-qc. The solid-state tutorials use the pob-* basis sets, designed specifically to avoid linear dependencies in periodic calculations.

The “properties & workflows” tutorials use run_job — the high-level entry point that writes .out / .molden / .traj files in one call, matching how classic QC programs work. The fundamentals tutorials use the lower-level drivers (run_rhf, run_rks, …) which give you direct access to result objects. The non-mean-field solvers tutorial covers both styles — run_job shortcuts and the low-level solver API.