近以自洽分子軌域法之分子內轉動研究

The Molecular Internal Rotation Study of Approximate Self-Consistent Molecular Orbital Method

陳成(Cheng Chen) ； 楊遠威(Yung-Wei Yang) ； 徐雙富(Shuang-Fuh Shyu) ； 黃炯家(Jeong-Jia Hwang) ； 邱宏達(Horng-Dar Chiou)

《化學》 48卷1期 (1990/03) Pp. 7-14

https://doi.org/10.6623/chem.1990002

摘要

自從我等提出s-p分開型INDO-MO理論後，曾先後成功地應用於原子化熱及自由基之超細偶合常數等研究。本研究首次應用上述s-p分開型INDO-MO進行分子能障及內轉動的計算。由於軌域內相關能(interorbital correlation energy) 比軌域間相關能(interorbital correlation energy) 大很多，而內轉動之角度變異時，軌域間相關能變異雖多，但能量的數值不大可以略去。因而內轉動所產生能障之能差中，相關能部份幾乎因由等量的軌域內相關能之互相抵消而近似於零。所以一般自治分子軌域法之基態能差來計算其能障之能差是可靠而有意義的。本研究用高能障V_3及低能障V_6類等形式的分子進行MO的計算，不同形式的分子均可算得合理的結果。往後將擬建立心-心排斥能之調整法，使計算值更接近各能障(V_3或V_6)之實驗值。

並列摘要

We have successfully applied the s-p separation model INDO．MO theory to the studies of beat of atomization and hyperfine couplig constant of free radicals since it was developed by us. We first apply s-p separation model INDO-MO method to the energy barrier and intern al rotation calculation in this work. Intraobital correlation energy usually is much larger than interorbital correlation energy. Although there are lots of interobital correlation energy terms involved in the internal rotation problem with dihedral angle varied, they are usually negligble. When we calculate energy difference in the internal rotation problem, the intraorbital correlation energy terms may be cancelled to each other. Therefore, it is reliable to apply the approximate self-consistent field molecular orbital method and use its energy difference of ground state with various dihedral angles for energy barrier problems. In this work, we apply high barrier, V_3, and low barrier. V_6, types of molecules in our MO caculation. Both case are reasonably calculated. If we calibrated the core-core repulsion terms, the better energy barrier (V_3 or V_6) wiII be obtained in the future for this problem.