User guide

Reference-style background: each page describes a single concept / API area in depth. Read the tutorials first if you’re new to vibe-qc.

Find the page from the task

I need to…	Start here	Then check
define charge, spin, and coordinates	Molecules	External structures
choose or inspect a Gaussian basis	Basis sets	Linear dependence, ECPs
choose HF, DFT, or correlation	Functionals, MP2 and double hybrids, CCSD	Planning tutorial
run Microsoft SKALA neural XC	SKALA-1.1	worked tutorial, Functionals, memory budget
reduce molecular SCF memory	SCF modes	Memory budget, direct-SCF tutorial
improve difficult SCF convergence	SCF convergence	Initial guess, solver framework
construct a crystal, slab, or wire	Periodic systems	Crystal lattices, slabs
choose a periodic Coulomb route	Periodic methods	Periodic JK routes
run the ab initio cyclic cluster model (experimental)	AICCM	chi-CCM, Gamma-CCM
converge a crystal calculation	k-points	Smearing, density fitting
select an integral engine or J/K algorithm (experimental)	Integral engines	MANTA developer reference, density fitting
understand files and provenance	Output files	Logging, citations
analyze IAO charges, spins and bonds	IAO analysis	Numerical comparisons
hand a wavefunction to another program	TREXIO	Output files, citations
open or automate a QVF result	QVF and vibe-view	vibe-view CLI
run on another host	Queue	Running

Tutorial, guide, or API reference?

• Use Methods: theory and status to choose a method: one page walks every family with its physics, its run_job spelling and its production, preview, experimental or gated label.

• Use a tutorial when learning a method or workflow. Tutorials include a runnable calculation, theory, expected output, and interpretation.

• Use this user guide for supported behavior, options, defaults, and limitations organized by concept.

• Use the API reference when you already know the object or function name and need its exact signature.

• Use the examples catalog to find a complete input closest to the job you want to run.

Molecular methods

• Molecules
• Basis sets
• Molecular basis-set optimisation
• Cohesive energies and the energy-engine abstraction
• Molecular naming
• Functionals
• Microsoft SKALA-1.1 neural XC
• ROHF and ROKS (restricted open-shell SCF)
• MP2 and double hybrids
• CC2, CC3, CCSD, CCSDT, QCISD, and perturbative triples
• TDDFT, TDA and CIS excited states
• DLPNO methods (MP2, CCSD, CCSD(T))
• Local correlation on crystals: periodic DLPNO-CCSD(T)
• Non-mean-field solvers (vibeqc.solvers)
• Green’s-function ionisation potentials and electron affinities (GF2 and OVGF)
• Composite “3c” methods
• Machine-learning interatomic potentials (MACE)
• Semiempirical Methods
• Semiempirical and MACE method comparison
• MSINDO (semiempirical INDO)
• DFT+U (Hubbard correction)
• Effective core potentials (ECPs)

Periodic methods

• Periodic systems
• Crystal lattices
• Slabs and adsorbates
• Green’s-function surface embedding
• k-point meshes
• Multi-k periodic SCF
• Ewald summation in periodic systems
• BIPOLE: Ewald-J-split periodic HF and DFT
• Plane-wave Hartree-J via GPW / GAPW
• Periodic-SCF methods: BIPOLE, GDF, GPW / GAPW
• Periodic JK routes, method-family parity policy
• The cyclic cluster model (CCM)
• AICCM: the ab initio cyclic cluster model (experimental)
• χ-CCM / aiccm2026dev-b (experimental)
• AICCM - Γ-CCM, the aiccm2026dev-a line (experimental)
• χ-CCM / aiccm2026dev-b: an independent finite-torus derivation
• χ-CCM / aiccm2026dev-b decisions and open questions
• COOP and COHP bonding analysis

SCF & convergence

• SCF convergence
• OpenTrustRegion orbital optimization
• Theory of OpenTrustRegion molecular SCF
• SCF Fock-build modes
• Eigensolvers and the operator contract
• Initial guesses
• Smearing (fractional occupations for periodic SCF)
• Metallic BZ integration: the Gilat-Raubenheimer net
• Linear dependence and screening in periodic SCF
• Density fitting (RIJ / RIJK / RIJCOSX)
• Integral engines: libint, MANTA, RI and BUPO
• MANTA integral providers
• Implicit solvation (CPCM / COSMO)
• Settings and defaults
• Memory budget

Workflows & properties

• Native Molecular Geometry Optimizer
• Relaxed coordinate scans
• Nudged Elastic Band (NEB)
• Transition-state searches: the dimer method, eigenvector following and the IRC
• Vibrational analysis: Hessians, frequencies, IR intensities and thermochemistry
• Equation of state: Birch-Murnaghan fits
• Molecular dynamics
• Post-SCF properties
• Bond analysis: Wiberg, NBO, EDA, IBOs, and orbital entanglement
• IAO charges, spin populations and IAO-Wiberg bonds
• IAO numerical comparisons and reproducible examples
• Band structure and density of states
• Volumetric data: cube, XSF, and BXSF files
• The data_library/ parameter-storage standard
• Experimental reference data (vqfetch reference)
• QTAIM: topological analysis of the electron density

Import & export

• ASE integration
• External QC codes (ORCA / Psi4 / others)
• External structures (vqfetch)
• Moving from PySCF
• Moving from CRYSTAL
• Moving from ORCA
• Moving from Gaussian
• Input scripts and output files
• TREXIO wavefunction files
• The output logger (vibeqc.output)
• Automatic citations

Tooling

• BLAS + LAPACK backend
• Running vibe-qc through the vq queue
• Running vibe-qc from Jupyter Lab
• Keyword index
• Basis-set toolkit

Looking for vibe-view or QVF?

The viewer and format reference pages (interactive viewer, terminal mode, desktop app, vq Job Manager, live reload, QVF job containers) are grouped with their tutorials and the format toolkit under QVF and vibe-view.