About this project

avo_ibo computes Intrinsic Bond Orbitals (IBOs) for closed-shell molecules via Psi4 for SCF and wavefunction generation, followed by IAO/2014 orbital construction and Pipek-Mezey localization. It supports occupied and valence-virtual IBOs with degeneracy resolution for on-atom and bond-flat cases. The tool outputs an analysis table (ibos.txt) detailing orbital occupancy, energy, bond type, atomic composition, hybridization, partial charges, and bond orders (including σ and π components). Molden files (ibo.molden, canonical.molden) are generated for orbital visualization in Avogadro. Available as an Avogadro 2 plugin (Extensions menu) or standalone CLI. Each calculation produces input.xyz, ibos.txt, ibo.molden, canonical.molden, and psi4.log in a run-specific directory. Limitations: Open-shell systems are unsupported. Symmetric molecules may exhibit small energy splittings in symmetry-equivalent orbitals. The analysis table uses the IAO basis for clean composition, while Molden isosurfaces include repolarization contributions, causing minor inherent inconsistencies.