Makarewicz Jan
Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL 60-780 Poznań, Poland.
J Chem Phys. 2005 Jul 22;123(4):044307. doi: 10.1063/1.1978868.
The structure and dynamics of the van der Waals complex of argon with the p-difluorobenzene cation are investigated using the ab initio theory. The restricted open-shell Møller-Plesset second-order perturbation method combined with the augmented correlation-consistent polarized valence double-zeta basis set is employed to determine the electronic ground-state potential-energy surface of the cationic complex. This surface is extremely flat in a wide region of the configuration space of the Ar atom which moves almost freely over the monomer ring. However, it is bound to the monomer stronger in the cationic than in the neutral complex. Its binding energy is calculated to be 621 cm(-1) at a distance of 3.445 A from the monomer center. The calculated dissociation energy of 572 cm(-1) agrees perfectly with the experimental value of 572+/-6 cm(-1) [S. M. Belm, R. J. Moulds, and D. Lawrence, J. Chem. Phys. 115, 10709 (2001)]. The effect of a strong coupling of large-amplitude intermolecular motions on the character of van der Waals vibrational states is investigated. The vibrational structure of the spectrum of the complex is explained and its earlier assignment is partly corrected.
采用从头算理论研究了氩与对二氟苯阳离子的范德华复合物的结构和动力学。使用受限开壳层莫勒-普莱塞特二阶微扰方法结合增强的相关一致极化价双ζ基组来确定阳离子复合物的电子基态势能面。在Ar原子构型空间的广阔区域内，该势能面极其平坦，Ar原子几乎可以在单体环上自由移动。然而，它在阳离子复合物中比在中性复合物中与单体的结合更强。计算得出，在距单体中心3.445 Å处，其结合能为621 cm⁻¹。计算得到的572 cm⁻¹的解离能与572±6 cm⁻¹的实验值[S. M. 贝尔姆、R. J. 莫尔兹和D. 劳伦斯，《化学物理杂志》115, 10709 (2001)]完全吻合。研究了大幅度分子间运动的强耦合对范德华振动态特征的影响。解释了复合物光谱的振动结构，并对其早期归属进行了部分修正。
