"The nature of the chemical bond is the problem at the heart of all chemistry."  -Bryce Crawford

At its core, the NBO program requires only minimal information from a host electronic structure system (ESS) program: the 1e density matrix (in unspecified AO basis) and the corresponding overlap matrix and angular symmetry labels (s,p,d,...) of the AOs. Neither the spatial forms of AOs (whether Gaussian-type, Slater-type, etc.) nor any other type of structural or energetic information is required for basic NAO/NBO/NLMO/NRT tasks.

However, many additional NBO analysis options (PLOT, 2nd-order energetic analysis, $DEL-deletions, NMR properties analysis, etc.) become available as additional information is provided from the ESS host. In many cases, the ESS/NBO information flow is passive and one-way (e.g., spatial information for PLOT output, or the converged Fock/Kohn-Sham matrix for energetic analysis, etc.), and non-interactive "stand-alone" GenNBO functionality suffices. However, more powerful ESS/NBO applications (such as $DEL-deletions or NEDA) require full two-way interactivity, which required binary linking in pre-NBO6 versions. That technical hurdle is removed in NBO7.

NBO7 is based on a message-passing protocol that allows free-standing ESS and NBO7 binaries to communicate and perform complex ESS/NBO7 "cooperative binary-pair" tasks. The NBO Team can provide the necessary snippets of template fortran freeware (and other technical assistance, as required) that allow your ESS program to begin interacting with an accessible NBO program.

The virtual ESS/NBO7 interface can be as simple or complex as you wish, depending on the message types you choose to implement (one- or two-way, services or requests for services, etc.). In principle, virtually any ESS can now implement the powerful $DEL-deletions, NEDA, NCS, and other interactive options that were previously accessible only in linked Gaussian/NBO5 or GAMESS/NBO5 configurations. In addition, many other types of NBO-based CAS/CC/CI methods and specialized property analyses can now be implemented to enhance the unique capabilities of your ESS.

Contact Eric Glendening (eric.glendening@indstate.edu) for further information on building NBO7-compatibility into your ESS program.

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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Program & Distributor



ADF: Software for Chemistry & Materials N.V.
[ADF2019 includes installed NBO6-level program that can also write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)...] ( more)]


DEMON2K: deMon Developers (demon-software.com)
[DEMON2k includes interface to write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)]


FIREFLY/PC-GAMESS: Alex Granovsky (Moscow State Univ.)
[Firefly (requires TCI/NBO password) includes installed NBO5-level program that can also write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)]


GAMESS(U.S.): Mark Gordon (Iowa State Univ.)
[GAMESS source version includes NBO7-compatible interfacing for plugin of NBO 7.0 and fully interactive GAMESS/NBO7 functionality...] (more)


GAUSSIAN: Gaussian, Inc.
[Gaussian 16 includes NBO7-compatible interfacing for plugin of NBO 7.0 and full G16/NBO7 binary-to-binary interactivity...] (more)


JAGUAR: Schrödinger, Inc.
[Jaguar includes installed NBO6-level program that can also write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)...] (more)


MOLCAS: Molcas.org (Univ. Lund)
[Molcas 8.2 includes older NBO3-level code (NPA only). In addition, Molden-type output from Molcas is convertible to valid NBO archive (.47) form as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol).] The eXatomic utility allows direct interfacing between [open]Molcas and recent NBO versions.


MOLPRO: H.-J. Werner (Univ. Stuttgart)
[ Molpro v. 2018 includes NBO7-compatible interfacing for source or binary level plugin of NBO 7.0 and fully interactive Molpro/NBO7 applications... (more)]


NWCHEM: Pacific Northwest National Laboratories
[NWChem includes interface to write valid NBO archive (.47) files as input for stand-alone GenNBO program (including that provided with NBO 7.0 or NBOPro@Jmol)]


ORCA: Frank Neese (MPI-Mülheim)
[Orca v. 4 includes NBO7-compatible interfacing for plugin of NBO 7.0 and fully interactive Orca/NBO7 binary-to-binary functionality...] (more)


PQS: Parallel Quantum Solutions
[PQS includes installed NBO5-level program that can also write NBO archive (.47) files as input to GenNBO program (such as that included in NBO 7.0 or NBOPro@Jmol]


PSI4: PSI4 Project (Va. Tech., Ga. Tech.)
[Psi4 includes interface to write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)]


Q-CHEM: Q-Chem, Inc.

[Q-Chem 5.0 includes both NBO6-compatible interfacing for interactive Q-Chem/NBO6 applications and installed NBO5-level program that can write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)] ( more)


SPARTAN: Wavefunction, Inc.
[Spartan'18 includes older NBO3-level code (NPA only)]


TERACHEM: PetaChem, LLC
[TeraChem includes installed NBO6-level interactivity that can also write valid NBO archive (.47) files as input for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol)...] ( User Guide, p. 16)]


TURBOMOLE: Turbomole GmbH
[Turbomole v. 7.3 includes older NBO3-level code (NPA only). In addition, Turbomole output is convertible to Molden format for generation of valid NBO archive (.47) files for stand-alone GenNBO programs (including that provided with NBO 7.0 or NBOPro@Jmol).]



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