The experimental charge-density approach in the evaluation of intermolecular interactions. Application of a new module of the XD programming package to several solids including a pentapeptide.
The experimental charge-density approach in the evaluation of intermolecular interactions. Application of a new module of the XD programming package to several solids including a pentapeptide.
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评估分子间相互作用的实验电荷密度方法。
DOI：
10.1107/s0108767300011405
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Coppens,P
中科院分区：
文献类型：
--
作者：
Abramov,YA;Volkov,A;Wu,G;Coppens,P
一个新的模块接口的XD编程包已被用于评价的分子间相互作用和晶格能的晶体的对硝基苯胺，l-天冬酰胺一水合物和五肽Boc-Gln-d-Iva-Hyp-Ala-Phol（Boc =丁氧基羰基，Iva =异缬氨酸=乙基丙氨酸，Phol =苯丙氨醇）。利用KRMM（κ′-restricted multipole model）修正的原子中心分布多极子模型，利用Buckingham非重叠电荷密度表达式计算了静电相互作用.对硝基苯胺的结果进行了比较与Hartree-Fock（HF），密度泛函（DFT）和Møller-Plesset（MP2）超分子计算和HF和DFT周期计算。HF和DFT方法未能预测对硝基苯胺晶体的稳定性，但实验电荷密度方法（ECDA）的结果与MP2相互作用能和实验晶格能都很好地吻合。L-天冬酰胺一水合物的ECDA结果与DFT超分子和周期HF计算的结果比较好。在实验温度20 K下，五肽中端基的无序状态持续存在，对应的能量差仅为0.35 kJ mol−1，这太小了，无法用现有方法重现。
A new module interfaced to the XD programming package has been used in the evaluation of intermolecular interactions and lattice energies of the crystals of p-nitroaniline, l-asparagine monohydrate and the pentapeptide Boc-Gln–d-Iva–Hyp–Ala–Phol (Boc = butoxycarbonyl, Iva = isovaline = ethylalanine, Phol = phenylalaninol). The electrostatic interactions are evaluated with the atom-centered distributed multipoles from KRMM (κ′-restricted multipole model) refinements, using the Buckingham expression for non-overlapping charge densities. Results for p-nitroaniline are compared with Hartree–Fock (HF), density functional (DFT) and Møller-Plesset (MP2) supermolecular calculations and with HF and DFT periodic calculations. The HF and DFT methods fail to predict the stability of the p-nitroaniline crystal but the results of the experimental charge-density approach (ECDA) are in good agreement with both MP2 interaction energies and the experimental lattice energy. ECDA results for l-asparagine monohydrate compare well with those from DFT supermolecular and periodic HF calculations. The disorder of the terminal group in the pentapeptide, which persists at the experimental temperature of 20 K, corresponds to an energy difference of only 0.35 kJ mol−1, which is too small to be reproduced with current methods.