"It is nice to know that the computer understands the problem, but I would
like to understand it too."
- Eugene Wigner|
The Natural Bond Orbital (NBO) program NBO 7.0
is a discovery tool for chemical insights from
complex wavefunctions. NBO 7.0 is the current
version of the broad suite
of 'natural' algorithms for optimally expressing numerical solutions of
Schrödinger's wave equation in the chemically intuitive
language of Lewis-like bonding patterns and associated resonance-type
Through their close association with elementary Lewis structure
diagrams, NBOs provide a direct link to familiar valency
and bonding concepts. Unlike delocalized MOs
(whose sprawling forms vary bewilderingly even between closely
related systems), NBOs are highly conserved
and transferable from one molecular environment
NBOs are local eigen-properties of the input wavefunction,
the intrinsic realizations of orbital-type bonding concepts
as originally envisioned by Pauling, Mulliken,
and Coulson. Unlike methods based on derivatives
of charge density (a quasi-classical concept), NBO analysis exhibits
the unifying beauty of quantum phase-matching and
in all chemical phenomena.
NBO provides mutually consistent and comprehensive
analysis tools, ensuring harmonious chemical
interpretations from one property to another. The program is
uniformly implemented in leading electronic
structure packages, providing an authoritative framework for
state-of-the-art professional discourse. Widespread acceptance
of the NBO paradigm is reflected in the burgeoning number
of published applications (currently, >2000 per year).
[Check here for latest bugfix
and update announcements]
November 15, 2018: NBO7 ANNOUNCEMENT DAY
NBO 7.0 is announced!
Following years of program development
and cooperation with affiliated ESS providers,
leading members of the NBO Team
(Eric Glendening, Frank Weinhold, Clark Landis) unveiled
website and announced public
availability of the
program, as well as enhanced
Claisen rearrangement illustrated with Resonance NBOs (RNBOs),
newest addition to the NBO-based orbital family
November 19, 2018:
Temporarily, NBO 7.0 for PC-Windows is being released
only in 32-bit binaries without functioning MEMORY
keyword for dynamic memory allocation. (The default
scratch memory is still 1Gb, equivalent to that of
the intended 64-bit implementation.)
Watch here for notification when the full-featured 64-bit
NBO 7.0 binary for PC-Windows
(equivalent to linux and MacOSX binaries) replaces the
temporary 32-bit version in the website distribution link,
at which time licensed purchasers of NBO 7.0 (PC-Windows)
can download the 64-bit program at their convenience.
[Jan. 2, 2019 Update: New NBO7 release "7.0.2"
that cures this PC-Windows issue is
now available for download by all licensed NBO7
and NBOPro@Jmol purchasers.]
November 20, 2018:
If you purchased NBO 6.0 in the last few
weeks before NBO 7.0 release
(specifically, in the period
October 15-November 15, 2018), you are eligible for
a 50% refund on the purchase price for immediate
upgrade to current NBO 7.0 (offer expires
December 15, 2018). Contact Cara Jenkins
(firstname.lastname@example.org) with your NBO7 license information
to request the refund.
December 5, 2018:
Early Download Problems: In early NBO7 purchases,
the email sent to license holders contained the wrong
link (the legacy NBO6 download link). The correct link
address for NBO7 downloads should end in "nbo7.cgi"
(not "nbo6.cgi"). Our apologies!
December 18, 2018:
Early Download Problem for NBOPro@Jmol:
In the initial download package for NBOPro@Jmol,
the .zip file failed to include the "unix2dos"
utility that is needed for RUN, VIEW, and SEARCH
modules. All NBOPro@Jmol license holders should obtain
a fresh download package with the download code
provided at time of purchase. Our apologies!