کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5415404 1393755 2010 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A new torsion-rotation fitting program for molecules with a sixfold barrier: Application to the microwave spectrum of toluene
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
A new torsion-rotation fitting program for molecules with a sixfold barrier: Application to the microwave spectrum of toluene
چکیده انگلیسی
A new program is described for fitting rotation-torsion energy levels in molecules like toluene, in which the frame (C6H5) has C2v symmetry and the methyl top has C3v symmetry, i.e., for molecules where the internal rotation barrier is expanded in cos6nα, where α is the internal rotation angle and n = 1,2,…. The program is based on the theoretical framework developed by Sørensen and Pedersen in their application of the Longuet-Higgins permutation-inversion group G12 to the microwave spectrum of CH3NO2. It is specifically designed for sixfold barrier molecules, and allows the user to select almost any symmetry-allowed torsion-rotation term for inclusion in the fitting Hamiltonian. This program leads to a very successful fit of transitions in the microwave spectrum of toluene characterized by J ⩽ 30, Ka ⩽ 12, and by the free-rotor quantum number ∣m∣ ⩽ 3. In these fits we included both published and rather extensive unpublished new measurements, for which fits using other torsion-rotation programs have not been very successful. The fit presented here uses 28 parameters to give an overall standard deviation of 7.4 kHz for 372 line frequencies, and results in a much improved value for the sixfold barrier for toluene, V6 = 13.832068(3) cal mol−1.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Spectroscopy - Volume 259, Issue 1, January 2010, Pages 26-38
نویسندگان
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