The infrared fundamental intensities and polar tensor of allene

The polar tenser of allene was calculated from the infrared fundamental ban d intensities of C,H, and C,D,. The ambiguities in the signs of the dipole moment derivatives with respect to their normal coordinates were resolved b y comparison of tenser elements with ab initio calculations at the B3LYP, M P2(FC) and CCD(FC) levels with a 6/311 + + G(3d,3p) basis set. The results are similar to those previously obtained by Koga and co-workers except for the choice of an average of two sign combinations fur the E symmetry elemen ts. The values of the mean dipole moment derivatives for the sp and sp(2) c arbon atoms obtained in this work, 0.032 and -0.133 e, respectively, are in good agreement with the CCD(FC)/6-311 + + G(3d,3p), 0.061 and - 0.128 e, a nd MP2(FC)/6-311 + + G(3d,3p), 0.072 and -0.153 c, theoretical results. The mean dipole moment derivatives are shown to be consistent with potential m odels relating Is electron ionization energies and atomic charges. (C) 2001 Elsevier Science B.V. All rights reserved.