Experimental¶
vibe-qc ships a handful of features behind an experimental gate. They are
reachable, but not yet production-certified and subject to change without the
usual deprecation cycle. Each one emits an ExperimentalWarning when used.
What’s in this section¶
The feature catalog is the complete table of every gated feature, its opt-in, its caveat, and its quantitative-status column. Start there if you want to know what’s gated and why.
Basis set development, developer documentation for the basis-set optimiser toolchain, design notes, and verification reports.
AICCM, the ab-initio cyclic cluster model, both Γ-CCM (
aiccm2026dev-a, direct-torus) and χ-CCM[1] (aiccm2026dev-b, finite-character (Γ-centred character-mesh)).
Basis set development¶
Basis set development
AICCM: ab-initio cyclic cluster model¶
The cyclic cluster model is vibe-qc’s signature real-space approach to periodic systems. Two independent implementations are maintained while the common limit is being established:
aiccm2026dev-a, the direct-space Gamma-supercell CCM line (vibeqc.periodic.ccm). Full HF, KS, MP2, CCSD(T), and DLPNO stack on the BvK torus, with open-shell UCCSD(T) and derivable properties.aiccm2026dev-b, χ-CCM, the finite-character (Γ-centred character-mesh) CCM line (vibeqc.periodic_aiccm2026dev_b). It uses the explicit Γ-centred character net, 1D/2D/3D RHF/RKS/UHF/UKS plus RI-MP2 and local-PNO CCSD(T).
Open-shell capabilities across both lines are documented in Open-shell AICCM.
AICCM reference
AICCM tutorials
AICCM experimental
AICCM examples¶
The runnable examples live under examples/periodic/:
aiccm2026dev_a_demo.py, Γ-CCM full stack: 8-fold ERI symmetry check on 1-D/2-D/3-D lattices, the HF→MP2→CCSD(T) correlation ladder, and the Madelung-background diagnostic on the neutral four-center.aiccm2026dev_b_demo.py, χ-CCM: exercises all three ER backends in 1D, 2D, and 3D.aiccm2026dev_b_mp2.py, canonical RI-MP2 in 3D.aiccm2026dev_b_local_correlation.py, DLPNO-MP2 and DLPNO-CCSD(T) on the χ-CCM finite torus.aiccm2026dev_diamond_bonds_bands_compare.py, matched diamond HF/KS input for Γ-CCM/χ-CCM bond orders, band structures, and localized-orbital QVF archives.benchmark_aiccm2026dev_b.py, H4 convergence comparison against the historical and Γ-CCM weights.
The full Γ-CCM/χ-CCM/CRYSTAL fleet experiment inputs live under
aiccm-2026/.
AICCM documentation map¶
you want to… |
read this |
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Get a number in 30 seconds |
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Run your first Γ-CCM calculation |
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Run your first χ-CCM calculation |
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See all Γ-CCM methods and routes |
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See all χ-CCM methods, backends, and caveats |
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Run open-shell (UHF, UCCSD(T)) |
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Compare Γ-CCM and χ-CCM head-to-head |
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Choose the right basis set |
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Debug a failing calculation |
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Generate orbital/density visualizations |
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Understand the broad CCM concept |
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Understand the χ-CCM derivation |
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Understand the theory (Γ-CCM paper) |
See also¶
Roadmap, the v2.x CCM track and where this work fits.
Troubleshooting, known bugs and workarounds.
The comparative manuscript, detailed theory record for the Γ-CCM and χ-CCM streams.