OPBAS Search Help

The OPBAS option gives access to individual matrix elements of a chosen Operator in a chosen Basis. Desired matrix elements can be specified by explicit r(ow), c(olumn) indices, or one can search for minimum/maximum values within a given row or column, or anywhere in the matrix.

For a selected job (chosen here as the water dimer, "w2.47"), clicking OPBAS leads first to a menu of available 1e operators, as shown below:

For the present example, we select K (kinetic energy operator), Basis = NBO, and row, column values corresponding to the p-rich O(1) lone pair (NBO 4) and O(4)-H(6) hydride antibond (NBO 10). For these settings, we request ⟨r|K|c⟩ values for current (r,c) and extremal (minimum/maximum) values for various wild-card (*r, *c) combinations, as shown below:

From the results in Session Dialog, one can see that

⟨4|K|14⟩ = -0.4146 a.u.
max ⟨4|K|*⟩ = ⟨4|K|15⟩ = 2.0317 a.u. (largest value in row 4, at column 15)
min ⟨4|K|*⟩ = ⟨4|K|1⟩ = -2.9506 a.u. (most negative value in row 4, at column 1)

and so forth. Such options allow one to efficiently "data-mine" the localized matrix representations of chosen quantum mechanical operators for values of special interest.

[No OPBAS search results are included in default NBO output, so each may require a RUN pause for directed re-analysis when first requested.]

References:
NBO Manual, Sec. B.2.4.