Ab initio molecular dynamics simulation of methanol and acetonitrile: The effect of van der Waals interactions

RF Dias and CCA Costa and TM Manhabosco and AB de Oliveira and MJS Matos and JS Soares and RJC Batista, CHEMICAL PHYSICS LETTERS, 714, 172-177 (2019).

DOI: 10.1016/j.cplett.2018.10.085

We employed PBE and BLYP semi-local functionals and the van der Waals density functional of Dion et al. (2004) (vdW-DF) to investigate structural properties of liquid acetonitrile and methanol. Among those functionals the vdW-DF is the only one that correctly predicts energy minima in inter-molecular interactions between acetonitrile molecules. We found that van der Waals interactions have a negligible effect on H-bonds in methanol chains. However, it significantly increases chain packing resulting in a more dense liquid in comparison to the other two functionals. The overall trend is that the vdW-DF tends to overestimate density and bulk modulus, meanwhile the semi-local functionals tend to underestimate density. Thus, van der Waals interactions play an important role in the properties of liquids in which much stronger dipole-dipole interactions are present.

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