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.
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,
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
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
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.