ine-Tuning the Polarizable CL&Pol Force Field for the Deep Eutectic Solvent Ethalin

Author(s)

de Souza, Rafael Maglia ^[1] ; Karttunen, Mikko ^{[2, 3, 4, 5]} ; Costa Ribeiro, Mauro Carlos ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, BR-05508070 Sao Paulo - Brazil

^[2] Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7 - Canada

^[3] Univ Western Ontario, Dept Chem, London, ON N6A 5B7 - Canada

^[4] Univ Western Ontario, Ctr Adv Mat & Biomat Res, London, ON N6A 5B7 - Canada

^[5] Russian Acad Sci, Inst Macromol Cpds, St Petersburg 199004 - Russia

• Document type: Journal article
• Source: JOURNAL OF CHEMICAL INFORMATION AND MODELING; v. 61, n. 12, p. 5938-5947, DEC 27 2021.
• Web of Science Citations: 1

Abstract

Polarizable force fields are gradually becoming a common choice for ionic soft matter, in particular, for molecular dynamics (MD) simulations of ionic liquids (ILs) and deep eutectic solvents (DESs). The CL\&Pol force field introduced in 2019 is the first general, transferable, and polarizable force field for MD simulations of different types of DESs. The original formulation contains, however, some problems that appear in simulations of ethaline and may also have a broader impact. First, the originally proposed atomic diameter parameters are unbalanced, resulting in too weak interactions between the chlorides and the hydroxyl groups of the ethylene glycol molecules. This, in turn, causes an artificial phase separation in long simulations. Second, there is an overpolarization of chlorides due to strong induced dipoles that give rise to the presence of peaks and antipeaks at very low q-vector values (2.4 nm(-1)) in the partial components of the structure factors. In physical terms, this is equivalent to overestimated spatial nanoscale heterogeneity. To correct these problems, we adjusted the chloride-hydroxyl radial distribution functions against ab initio data and then extended the use of the Tang-Toennis damping function for the chlorides' induced dipoles. These adjustments correct the problems without losing the robustness of the CL\&Pol force field. The results were also compared with the nonpolarizable version, the CL\&P force field. We expect that the corrections will facilitate reliable use of the CL\&Pol force field for other types of DESs. (AU)

• FAPESP's process: 20/06766-9 - Molecular dynamics of deep eutectic solvents
• Grantee: Rafael Maglia de Souza
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 16/21070-5 - Vibrational spectroscopy with spatial resolution
• Grantee: Mauro Carlos Costa Ribeiro
• Support Opportunities: Research Projects - Thematic Grants