Structural investigation of room-temperature ionic liquids and high-temperature ionic melts using triplet correlation functions

We use means of molecular dynamics simulation to understand the local structural arrangements in three trihexyltetradecylphosphonium (P6,6,6,14+) based room-temperature ionic liquids (RTILs) by using triplet correlation functions (TCFs) along with pair correlation functions (PCFs) and X-ray scattering structure functions (S(q)s). The anions in these RTILs are either spherically symmetric but with different effective sizes (bromide (Br−) and tetrafluoroborate (BF4−)) or angular such as dicyanamide (DCA−). The simulated PCFs, S(q)s, and TCFs of the three RTILs have been compared with three high-temperature ionic melts (HTIMs); NaBr, NaCl, and NaF. In general, the pair correlation function gives angle-averaged probability as a function of inter-particle distance whereas the TCFs associated with equilateral and isosceles triangle configurations can be used to delineate angle-resolved information of liquids structure within nearest solvation shells. For the three ionic liquids studied, a very careful examinati...