You may include other keywords such as BNDIDX which generates a Wiberg bond index ( order) matrix or BOAO which generates the same matrix but in the Natural Atomic Orbitals basis. NOTE: I have my own issues and concerns about the use of DFT along with NBO but maybe that will be treated in another post.Īt the end of the input file, after the infamous blank line type the following: This calculation requests a geometry optimization followed by a Natural Bond Orbital population analysis (with keywords to be read) using the Restricted Hartree-Fock method with the split valence basis set 6-31G(d,p) #P opt rhf/6-31G(d,p) pop=(full,nboread) gfoldprint geom=connectivity Make sure that the route section in your input file includes the following options: pop=nboread gfoldprint (in case you are using G03 or even G09) or gfprint (in case you are still running G98), e.g.:
#Gaussian 09w utilities manuals#
Most of the answers are concerned with what visualization programs to use but they seldom provide step by step instructions, furthermore most manuals are a bit cryptic about the procedure to plot this orbitals. Visualizing them, however is never a straightforward process, and quite often we see more questions on the CCL than answers trying to address the matter. So far I have only worked with Gaussian 98, Gaussian 03 and only recently with Gaussian 09 in calculating NBO’s although it is possible also to perform them with GAMESS and the standalone NBO5.0 program created by Frank Weinhold. Another advantage of the NBO analysis is that it provides a localized depiction of the electron density over a molecule, making it more related to chemists intuition. is highly sensitive to basis set effects. The Natural Bond Orbitals analysis is a powerful tool in population analysis calculations which is more robust than the traditional Mulliken approach, if for no better reason because its almost insensitive to the change of basis set while Mulliken’s P.A. This is the second post on a series which will try to address common technical questions in computational chemistry that recursively appear on the CCL.