Whats Under the Hood

A general overview of the subprograms of Groups 1 and 11 (all called by the highest-level SR RUNNBO) is shown in the accompanying flow chart, which indicates the logical relationship of the routines to one another and to the order of discussion in Sections C.5 and C.6 of the NBO Manual. The sequence of execution is 

Discovering Chemistry With Natural Bond Orbitals, First Edition. Frank Weinhold and Clark R. Landis. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

Each program module is in turn related to a particular subsection and key word(s) of Section B, such as default NPA/NBO analysis (Section B-2), NRT analysis (Section B-72), STERIC analysis (Section B-lOO), and so forth. For any particular subroutine or function of the NBO program, you can look up its index entry under SUBROUTINE or FUNCTION and find its detailed description in Section C of the NBO Manual. At the beginning of each keyword subsection in Section B, you will generally find an original literature citation that describes the underlying NBO algorithm and 

Section B also contains additional information on individual keyword options, including syntax of varied DEL options (p. B-16ff), rules for constructing SCHOOSE B-14ff) and NRTSTR (p. B-77ff) keylist input, details of ARCHIVE 

Section C also provides useful information on program limits and thresholds (consult individual THRESHOLD entries in the Index), default logical file numbers of user-requested external files (p. C-lOff), internal details of the NBO direct access (read-write) file (p. C-16ff) and other program control variables or error indices that may be referenced in error messages (cf. Appendix D). Keeping the NBO Manual close at hand and knowing how to troubleshoot with Sections B and C can solve many problems before it becomes necessary to contact nbo chem.wisc.edu for further assistance. 

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