| Abstract
| - One- and two-dimensional nuclear Schrödinger equations have been solved on MP2/aug‘-cc-pVDZ potentialenergy surfaces generated for ClH:NH3 and ClH:N(CH3)3 and on MP2/6-31+G(d,p) surfaces generated forBrH:NH3 and BrH:N(CH3)3 to investigate deuterium substituent effects on the expectation values of X−Nand X−H distances and on anharmonic dimer- and proton-stretching frequencies. These studies have beencarried out on all isotopomers in the presence of electric fields of varying strengths. Deuteration of HX orammonia or trimethylamine has only minor effects on expectation values and dimer-stretching frequencies.While deuteration of the nitrogen base also has only a minor effect on proton-stretching frequencies, deuterationof the hydrogen halide has a major effect, as expected. X−D stretching frequencies are always lower than thecorresponding X−H frequencies at all field strengths, although the ratio ν(D)/ν(H) for corresponding pairs ofisotopomers may be less than, equal to, or greater than the harmonic ratio of 0.71. Structural and vibrationalspectral changes as a function of field strength are similar for a given complex and each of its isotopomers.The agreement between computed proton-stretching frequencies and experimental frequencies supports thevalidity of this approach for modeling matrix effects on the structures and vibrational spectra of hydrogen-bonded complexes. The computed results provide insight into the nature of the hydrogen bonds that stabilizethese complexes in low-temperature matrixes.
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