Example: NBO analysis: adfnbo, gennbo¶
Dr. Autschbach, SCM, and Prof. Weinhold have collaborated to prepare a simple in put file generator, called adfnbo, for the GENNBO program of Prof. Weinholds Natural Bond Orbital (NBO) 6.0 package: http://nbo6.chem.wisc.edu The GENNBO executable is included in the ADF distribution and can be enabled via the license file ( info@scm.com).
Usage:
$ADFBIN/adf <<eor
Title simple NBO example for water
Atoms Z-Matrix
O 0 0 0
H 1 0 0 0.9
H 1 2 0 0.9 100
End
Basis
CORE NONE
TYPE DZ
End
FULLFOCK
AOMAT2FILE
SAVE TAPE15
SYMMETRY NOSYM
End Input
eor
$ADFBIN/adfnbo <<eor
write
fock
spherical
end input
eor
$ADFBIN/gennbo6 FILE47
Note added: recommended is to use the key ‘spherical’ in the adfnbo input.
A File named FILE47 is generated by adfnbo which is an input file for the general NBO program gennbo. ADF needs to write some data to file, which is done by including these keywords in the adf input file:
FULLFOCK
AOMAT2FILE
SAVE TAPE15
SYMMETRY NOSYM
GENNBO
Next a brief summary of the capabilities of GENNBO is given (by Prof. Weinhold). GENNBO implements most capabilities of the full NBO 6.0 program suite as described on the NBO website: http://nbo6.chem.wisc.edu These include determination of natural atomic orbitals (NAOs), bond orbitals (NBOs), and localized MOs (NLMOs), as well as the associated NPA (atomic charges and orbital populations) and NRT (resonance structures, weightings, bond orders) valence descriptors, for a wide variety of uncorrelated and correlated (variational, perturbative, or density functional) theoretical levels. GENNBO-supported options include all keywords except those explicitly requiring interactive communication with the host electronic structure system (viz., $DEL deletions, NEDA, NCS, NJC). The GENNBO program typically sits conveniently on the PC desktop, ready to analyze (or re-analyze at will, with altered options) the final results of a complex ADF calculation performed on a remote cluster.
GENNBO “communicates” with the original ADF calculation through an archive file (JOB.47 file, preserving all necessary details of the final density) that is initially generated by ADF and subsequently becomes the input file for GENNBO. The .47 file contains a standard $NBO ... $END keylist that can be edited with a standard word processor or text editor to include chosen NBO keyword options, just as though they might have appeared in the original input stream of an interactive ADFNBO run. The stand-alone GENNBO program therefore allows many alternative NBO analysis options to be explored at leisure, without costly re-calculation of the wave function.
Using the GENNBO executable is possible only if NBO6 is enabled in your license file by SCM ( info@scm.com). In that case you will get access to an NBO 6.0 manual in electronic form that explains in detail how GENNBO can be used and how the output should be interpreted.