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New NBO 7.0 Features

  • NEDA for Gaussian
    Based on the enhanced "link-free" interactive connectivity to the Gaussian host program (G16 Rev. C01 and beyond), NBO 7 now provides full G16/NBO7 implementation of Natural Energy Decomposition Analysis (NEDA keyword), previously available only in the GAMESS implementation. Uniquely among the many "EDA" variants, the NAO-based NEDA components avoid the ambiguities and illusions of nonorthogonal basis functions for interpenetrating monomer or "reference fragment" densities.

  • Convex-Solver NRT
    NBO 7 introduces a fundamentally new implementation of Natural Resonance Theory (NRT) analysis, based on convex-programming algorithms that yield improved robustness and accuracy of resonance-type descriptors for an expanded range of chemical applications. These NRT advances also build on improvements in $CHOOSE algorithms to avoid certain artifacts of apparent hypervalency and symmetry breaking that affected some NRT applications in NBO 6.

  • Natural Poly-Electron Population Analysis (NPEPA)
    NBO 7 introduces a full "natural" implementation of the "poly-electron population analysis" of Karafiloglou and coworkers [P. Karafiloglou and G. Ohanessian, J. Chem. Educ. 68, 583-586 (1991)] that generalizes single-electron population analysis (NPA) to a vastly expanded range of poly-electronic "electron-hole" patterns in complex wavefunctions. The NPEPA algorithms allow Born-type probabilities of default [E(2)-like] or user-selected donor-acceptor patterns (each envisioned as a "resonance structure" contribution to Ψ) to be efficiently evaluated for a broad variety of correlated (CI/CAS) or uncorrelated (HF/DFT) theory levels.

  • 2nd-Order Reduced Density Matrix (RDM2) Elements
    Coming soon...

  • Resonance NBOs (RNBO)
    NBO 7 provides the RNBO ("resonance" NBO) algorithm that combines NRT-based description of a continuously variable reaction coordinate to give the optimal set of semi-localized "bond-shifting" orbitals along the chosen pathway. The RNBOs are developed for visualization purposes, associated with a specified reaction pathway, and intended to display the strong 3-center (or higher multi-center) character and dynamical details of "curly arrow" delocalizations when viewed in an animated sequence. RNBOs can be distinguished from other localized or semi-localized MOs by their unique relationship to NRT resonance structures and bond orders. The occupied Lewis-type RNBOs can also serve as highly efficient building blocks for constructing many-electron wavefunctions or DFT densities.

  • Full Line of 64-bit PC-Windows, MacOSX, and Linux/Unix Binary Options for Stand-Alone or Interactive Usage
    NBO 7 is available in binary .exe form for PC-Windows, MacOSX, and Linux/Unix operating systems (based on 32-bit or 64-bit integers) running on 64-bit processors, as well as in source form. For stand-alone GenNBO usage, just include the "ARCHIVE" and "FILE=jobname" keywords in a standard NBO-linked electronic structure job (including those from earlier NBO versions) to obtain the "jobname.47" file that allows you to run alternative analyses (without recomputing the wavefunction) from the convenience of your PC/Mac/Linux laptop or desktop. Alternatively, simply include binary NBO7 in the environment of your NBO7-compatible host ESS to see the cooperating ESS/NBO7 binary pair "come to life" through message-passing to tackle complex interactive tasks.

NBO 7.0 is designed to be maximally compatible with NBO6 or other legacy NBO versions. Experienced NBO users will find that familiar options run practically unchanged, with smooth and intuitive migration to newer keywords, features, and output format.

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