ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The Thomas–Reiche–Kuhn sum rule, within the acceleration gauge for the transition dipole moment, is used to partition the total number of electrons in a molecule and to define atomic populations, which can be related to corresponding experimental estimates of atomic polar tensors from IR intensities. As a bond dipole moment can only be defined for diagonal atomic polar tensors, it is shown that the assumption of a C–H bond moment, transferable from molecule to molecule in the alkane series, is physically unreliable. From experimental IR intensities of methane we infer that, for the equilibrium geometry, μC–H =0.339 D, directed C−H+. Accordingly, it is argued that the theoretical bond dipole moments, estimated for the C–H bond in methane via localization procedures of SCF wave functions, are questionable, as they predict the opposite polarity. Finally, a resolution of the electric dipole moment into atomic contributions is suggested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.453232
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