One cannot understand ... the universality of the laws of nature, the relationship of things, without an understanding of mathematics. There is no other way to do it." - Richard Feynman

The NBO 6.0 website and associated order link and download site remain active at present. However, NBO6-level products are no longer updated for minor bug-fixes or other algorithmic improvements.

The NBO 5.0 website and associated order form (for NBO5-level versions that link with older ESS versions) has been removed from service (October 2017).

Still older legacy code (such as the 1980s-vintage "NBO 3.1" included in current Gaussian distributions) is not supported by the NBO development team and is not considered to be of publishable reliability except for routine organic applications in modest basis sets. Users encountering difficulties with legacy NBO code should contact the help desk of the host ESS that provides such code.

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NBO 7.0

NBO 7.0

Natural Bond Orbital Analysis program
As delivered, the basic NBO binary executable file is a slave program that can communicate cooperatively with any NBO7-compatible front-end host program in one of two possible modes:
(i) With the "gen" front-end (included in the standard download package, or provided by ESS host programs that include NBO7), one can launch the "gen + nbo" binary pair (GenNBO) to perform stand-alone (non-interactive) options with any valid NBO archive file (jobname.47) as input;
(ii) With any NBO7-interactive ESS as host front-end (currently, Gaussian, GAMESS, ORCA, or Q-Chem), one can similarly launch the "ESS + NBO" binary pair (ESSNBO) to perform interactive options supported by the host, or any non-interactive option as described in (i).
[NBO 7.0 is available as a 64-bit binary executable (.exe) program for linux/mac/unix or PC-Windows platforms, or in source fortran code for compilation/linking on other platforms.]



NBOPro plugin for the Jmol 3D viewer
The multi-modular electronic capabilities of NBOPro have now been "plugged in" to the powerful graphical capabiliies of the Jmol 3D chemical structure viewer:

NBOPro@Jmol is composed of four interacting program modules:
  (1) Model: A full-fledged molecular design editor and quantum-chemical file-conversion utility, complementing capabiities of the Jmol host program;
  (2) Run:Full-fledged GenNBO 7.0 capability to perform NBO7-level analyses of any available wavefunction archive (.47) file;
  (3) View: Full-fledged NBOView 2.0 ray-tracing capability, now enhanced with coordinated Jmol graphics to provide a new standard of graphical beauty, accuracy, and convenience for all NBO-related visualizations (still or video);
  (4) Search: Interactive "data miner" module that directly answers a broad range of questions about NBO analysis results of interest (including visual images, descriptor compilations, search for extremal values, etc.), even if the user has no familiarity with NBO analysis files that are generated and searched (in background) to provide the answers.

NBOPro@Jmol is the ultimate tool for "file-free" pedagogical and research-level NBO applications.

[NBOPro@Jmol is available as a 64-bit binary executable (.exe) program for PC-Windows platforms. The distribution package includes all necessary host Jmol.jar and slave GenNBO 7.0 and raytracer viewing components for immediate "load and go" applications with any available wavefunction archive (jobname.47) file, including the large number of .47 files available on the NBOrXiv website.]

Firefly NBO password Required password to activate NBO options in the Firefly (PC-GAMESS) program.

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