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首页> 外文期刊>The Journal of Chemical Physics >THE STRUCTURE AND BINDING ENERGY OF K+-ETHER COMPLEXES - A COMPARISON OF MP2, RI-MP2, AND DENSITY FUNCTIONAL METHODS
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THE STRUCTURE AND BINDING ENERGY OF K+-ETHER COMPLEXES - A COMPARISON OF MP2, RI-MP2, AND DENSITY FUNCTIONAL METHODS

机译：K +-醚络合物的结构和结合能-MP2，RI-MP2和密度函数方法的比较

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摘要

The structures and binding energies of several cation:ether complexes (K+:dimethyl ether, K+:dimethoxyethane, K+:12-crown-4 and K+:18-crown-6) were determined with second and fourth order perturbation theory using correlation consistent basis sets. Several of these are the largest correlated calculations yet attempted on crown ethers. The observed systematic convergence to the complete basis set limit provides a standard by which the accuracy of previous studies can be measured and facilitates the calibration of density functional methods. Recent Fouler transform ion cyclotron resonance experiments predicted K+:18-crown-6 binding energies which were significantly smaller than ab initio calculations. None of the potential sources of error examined in the present study were large enough to explain this difference. Although the 6-31+G* basis set used in an earlier theoretical study was smaller than the smallest of the correlation consistent basis sets, with suitable correction for basis set superposition error, it appears capable of yielding binding energies within several kcal/mol of the basis set limit. Perturbation theory calculations exploiting the ''resolution of the identity'' approximation were found to faithfully reproduce binding energies and conformational differences. Although the cation-ether interaction is dominated by classical electrostatics, the accuracy of density functional techniques was found to be quite sensitive to the choice of functionals. The local density SVWN procedure performed well for binding energies and conformational differences, while underestimating K+O distances by up to 0.08 Angstrom. The gradient-corrected Becke-Lee-Yang-Parr functional underestimated the K+:12c4 binding energy by 4-7 kcal/mol or 15%. (C) 1996 American Institute of Physics. [References: 52]
机译：利用二阶和四阶扰动理论，采用相关一致的基础，确定了几种阳离子：醚配合物（K +：二甲醚，K +：二甲氧基乙烷，K +：12-crown-4和K +：18-crown-6）的结构和结合能。套。其中一些是有关冠醚的最大相关计算。观察到的系统收敛到完整基集限制提供了一个标准，通过该标准可以测量以前的研究的准确性，并有助于校准密度泛函方法。最近的Fouler变换离子回旋共振实验预测K +：18-crown-6的结合能比从头算的要小得多。在本研究中检查的潜在错误源均不足以解释这种差异。尽管在较早的理论研究中使用的6-31 + G *基组小于相关的一致性基组中的最小基组，并通过适当校正基组叠加误差，似乎能够产生几kcal / mol的结合能。基本设置限制。发现利用“身份解析”近似的摄动理论计算可以忠实地再现结合能和构象差异。尽管阳离子-醚相互作用主要受经典静电的影响，但发现密度泛函技术的准确性对官能的选择非常敏感。局部密度SVWN程序在结合能和构象差异方面表现出色，但低估了K + O距离达0.08埃。经过梯度校正的Becke-Lee-Yang-Parr官能团低估了K +：12c4的结合能4-7 kcal / mol或15％。 （C）1996年美国物理研究所。 [参考：52]

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