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Revisiting OPLS-AA Force Field for the Simulation of Anionic Surfactants in Concentrated Electrolyte Solutions.
Journal of Chemical Theory and Computation ( IF 5.7 ) Pub Date : 2020-01-27 , DOI: 10.1021/acs.jctc.9b00947
Safwat Abdel-Azeim 1
Affiliation  

Hereby, we developed a set of nonbonded parameters within all-atom optimized potentials for liquid simulations (OPLS-AA) force field for the simulation of concentrated electrolyte solutions of anionic surfactants. More specifically, the aim of this paper is to assess the performance of five sets of atomic charges calculated using different population analyses (DDEC6, CHelpG, CHelpG-SMD, RESP, and CM5), as well as the original set of charges used in the literature for sodium dodecyl sulfate (SDS) simulation. Recently, Farafonov et al. have revised the SDS OPLS-AA force field; however, we were unable to obtain the experimental rodlike micelles using this parameter set on long time scale. In fact, the initial SDS bilayer micelle adopted a rodlike shape transiently and then broke down into spherical micelles. Updating OPLS-AA force field with DDEC6, CHelpG, and CHelpG-SMD charges resulted in stable rod micelles for a long simulation time (1 μs). The atomic charges of Farafonov (taken from Shelley et al.), RESP, and CM5 could not correctly describe SDS in concentrated electrolyte solutions. Analysis of the interaction of SDS with the counterions and solvent highlights the role of a balance of the intermolecular forces that must be met to describe adequately the anionic surfactant electrolyte solutions. Further, the optimization of the SDS Lennard-Jones parameters enabled the Farafonov set to properly reproduce the experimental rod micelle. In addition, we have examined the performance of different parameters of sodium ions: the first developed based on the Kirkwood-Buff integrals (KBI) and the second developed by Joung et al. The excessive ion pairing caused by KBI parameters screens significantly SDS-water interactions, which stabilize the rod micelle. Further, a tight interaction of the Na+-SDS head group resulted in stabilization of the bilayer micelle as observed in the case of Na+ parameters developed by Joung et al.

中文翻译:

再次探讨OPLS-AA力场,以模拟浓缩电解质溶液中的阴离子表面活性剂。

因此,我们在全原子优化的液体模拟(OPLS-AA)力场内开发了一组非键合参数,用于模拟阴离子表面活性剂的浓电解质溶液。更具体地说,本文的目的是评估使用不同的总体分析(DDEC6,CHelpG,CHelpG-SMD,RESP和CM5)计算出的五组原子电荷的性能,以及在原子色谱中使用的原始电荷集。十二烷基硫酸钠(SDS)模拟的文献。最近,Farafonov等。修改了SDS OPLS-AA力场;但是,我们无法长时间使用此参数集获得实验性棒状胶束。实际上,最初的SDS双层胶束瞬时呈棒状,然后分解为球形胶束。使用DDEC6更新OPLS-AA力场,CHelpG和CHelpG-SMD电荷可在较长的仿真时间(1μs)内产生稳定的棒状胶束。Farafonov(购自Shelley等人),RESP和CM5的原子电荷无法正确描述浓缩电解质溶液中的SDS。对SDS与抗衡离子和溶剂的相互作用的分析强调了分子间力平衡的作用,必须充分描述才能充分描述阴离子表面活性剂电解质溶液。此外,对SDS Lennard-Jones参数的优化使Farafonov装置能够正确复制实验棒胶束。此外,我们还研究了钠离子不同参数的性能:第一个基于柯克伍德-巴夫积分(KBI)开发,第二个由Joung等开发。由KBI参数引起的过量离子对显着屏蔽了SDS与水的相互作用,从而稳定了棒胶束。此外,在Joung等人开发的Na +参数的情况下,Na + -SDS头基之间的紧密相互作用导致双层胶束的稳定。
更新日期:2020-01-29
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