Natural Population Analysis (NPA)
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Reference
A. E. Reed, R. B. Weinstock, and F. Weinhold, J. Chem. Phys. 83, 735-746 (1985)
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Notes
Natural population analysis is performed by default ("NPA" keyword is optional). NPA leads to determination of natural atomic orbitals (NAOs; see Orbital Diagrams) and their occupancies, totalled to give the net "natural atomic charge" on each atom (see Sample Output). Results are illustrated for the formamide molecule, RHF/3-21G level at B3LYP/6-311++G** geometry (see NBO 6.0 Manual, pp. A13-15 for additional discussion).
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Sample Input (G9X)
#rhf/3-21g pop=nbo
RHF/3-21G for formamide (H2NCHO)
0 1
H -1.908544 0.420906 0.000111
H -1.188060 -1.161135 0.000063
N -1.084526 -0.157315 0.000032
C 0.163001 0.386691 -0.000154
O 1.196265 -0.246372 0.000051
H 0.140159 1.492269 0.000126