Taken from NBO-7 README and INSTALL.g16a03 files

Step 1: Unpack the distribution using tar, e.g.,

cp nbo7.0-bin-linux-x64.tar.gz /usr/local
cd /usr/local
tar -zxvf nbo7.0-bin-linux-x64.tar.gz

Step 2: Edit the gaunbo6 script in nbo7/bin.

Set the variables GAUNBO, BINDIR, and INT for your environment. For example, if NBO7 is installed in /usr/local and G16 uses 64-bit integers, set

setenv GAUNBO g16nbo
setenv BINDIR /opt/nbo7/bin
setenv INT i8

cd /usr/local/nbo7/bin

vim gaunbo6

#!/bin/tcsh -f

# See nbo7/tests/gaussian/a03/ALERT for G16 A.03 limitations.

# Use this script (gaunbo6) to perform NBO7 analysis with G09 and
# pre-C.01 revisions of G16. Use the gaunbo7 script with G16 C.01
# and later revisions.

# The directory containing this script should be present in the
# user's path during the Gaussian calculation. Alternatively, simply
# copying this file to $g09root/g09 or $g16root/g16, and editing it
# as described below generally works well.

# Inspect and set, as appropriate, the following three environment
# variables.

# Specify Gaussian interface (g09nbo or g16nbo):

setenv GAUNBO g16nbo

# Specify executable directory:

setenv BINDIR /usr/local/nbo7/bin

# Set integer presentation (i8 or i4, likely the former):

setenv INT i8

.....
.....
.....

Step 3: Ensure that the path to gaunbo6 is included in the path environment variable in your .bashrc

export PATH=$PATH:/usr/local/nbo7/bin

Note
NBO7 tests integer communications to ensure that G16 and NBO7 are using the same integer lengths. If NBO7 fails, try switching the integer length (i.e. from i8 or i4, or vice versa).

Users request NBO7 analysis using Gaussian keywords of the following forms:

pop=nbo6 — default NBO7 analysis, no $NBO input
pop=nbo6read — NBO7 analysis with $NBO input
pop=nbo6del — NBO7 analysis with deletions
pop=(nbo6,savenbos) — default NBO7 analysis, save NBOs, sorted by energy, on the checkpoint file
pop=(nbo6,savenlmos) — default NBO7 analysis, save NLMOs on the checkpoint file

Note that these keywords are analogous to the pop=nbo, pop=nboread, etc. keywords that are used to run the old NBO 3.1 analysis (Link 607) of G16.