期刊
JOURNAL OF PHYSICAL CHEMISTRY B
卷 116, 期 43, 页码 13024-13032出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp306110g
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资金
- CASPUR (Centro di Applicazione di Supercalcolo per Universita e Ricerca, Rome Supercomputing Center) [std11-465, std12-011]
- CINECA (IscrA_ASIL)
- Scientific Committee of the University of Rome
- European Commission [283883]
- FIRB [RBFR086BOQ]
- PRIN [2009WHPHRH]
In this study, we discuss the performance of classical molecular dynamics in predicting the experimental X-ray diffraction patterns of liquid ethylammonium nitrate (one of the simplest protic room-temperature ionic liquid showing amphiphilic behavior) and of its hydroxy derivative (2-ethanolammonium nitrate, 2-HOEAN). Newly recorded energy-dispersive X-ray diffraction structure factors are compared with the corresponding quantities extracted from molecular dynamics simulations. Other useful theoretical and experimental indicators are used as a probe of the local structure of the title ionic liquids. We shall show that the use of a general purpose, two-body terms only, force field, such as OPLS/AA is able to describe most of the structural experimental data. However, we shall also point out that an improved description of some key structural features observed in the X-ray radial distribution function, can be obtained very easily by adding a general three-body potential energy term instead of changing the two-body potential parameters, in order to optimize the agreement with experimental data. This three-body term turns out to be neurally able to describe the complex polarization effects due to hydrogen bonding without requiring a quanto-mechanical treatment or a polarizable force field. In addition the present model turns out to be able to account for the presence of a low-Q. peak in the scattering patterns of EAN, which has been commonly interpreted as a manifestation of the amphiphilic nature of this compound.
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