کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5418133 | 1506977 | 2007 | 12 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
A comparison between entropies of aromatic compounds from quantum mechanical calculations and experiment
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
In this work, we perform a set of quantum mechanical and statistical mechanical calculations to generate the entropy of five simple, aromatic compounds-benzene, toluene, p-xylene, m-xylene and o-xylene-in the ideal gas state. We systematically examine how the choice of quantum mechanical level of theory and size of basis set impact the agreement between theory and experiment. Regardless of level of theory and basis set, all calculations require an empirical scaling factor to correct the vibrational contribution to the entropy. Once this scaling factor is applied, there is at most nominal advantage in more sophisticated levels of theory or increased basis set size, while a heavy computational penalty is paid for the more advanced theory. We find that the variation in scaling factor across these aromatic compounds is on average 0.3%. Across a range from 250 to 540Â K, the difference in the entropies obtained from all quantum mechanical calculations and from experiment is less than half a percent.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure: THEOCHEM - Volume 802, Issues 1â3, 8 January 2007, Pages 23-34
Journal: Journal of Molecular Structure: THEOCHEM - Volume 802, Issues 1â3, 8 January 2007, Pages 23-34
نویسندگان
Mohamad H. Kassaee, David J. Keffer, William V. Steele,