کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9575349 1504346 2005 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Theoretical study of anharmonic vibrational spectra of HNO3, HNO3-H2O, HNO4: Fundamental, overtone and combination excitations
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Theoretical study of anharmonic vibrational spectra of HNO3, HNO3-H2O, HNO4: Fundamental, overtone and combination excitations
چکیده انگلیسی
Vibrational frequencies are computed for the fundamental, OH stretching overtone and combination transitions of HNO3, HNO4 and the HNO3-H2O complex. The frequencies are computed directly from ab initio MP2 potential surface points, using the correlation corrected vibrational self-consistent field (CC-VSCF) method, which includes anharmonic effects. The results are compared with experimental data. The computed fundamental transitions are in accord with experiment. The main improvement over the harmonic approximation is for the OH stretching frequencies. The OH overtone excitations (up to the 3rd overtone) of HNO3, HNO4 are also in good accord with experiment. For overtone levels near the dissociation threshold, the deviations from experiment are larger, as the VSCF method is unsatisfactory for the extremely large anharmonicities in these cases. Finally, very satisfactory results are obtained for the combination mode transitions. The main conclusions are (1) CC-VSCF seems to work well also for low overtone excitations and for combination transitions. (2) The MP2/TZP potential surfaces, used in the CC-VSCF calculations, are by the test of spectroscopy adequate for these species. The results are encouraging for VSCF calculations of larger, related systems such as HNO3-(H2O)n, n > 1.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 313, Issues 1–3, 27 June 2005, Pages 213-224
نویسندگان
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