Laboratório de Espectroscopia Molecular, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970, São Paulo, SP, Brazil.
J Chem Phys. 2013 Sep 21;139(11):114505. doi: 10.1063/1.4821227.
High-frequency collective dynamics of the ionic liquid 1-hexyl-3-methylimidazolium bromide, [C6C1im]Br, has been investigated by molecular dynamics simulations. Time correlation functions of mass current fluctuations were calculated for several wavevectors and the dispersion curves of excitations, ω(k), for longitudinal and transverse acoustic sound modes were obtained at different temperatures and pressures. Two different thermodynamic states have the same high-frequency sound velocity irrespective of the temperature provided that both have the same density. Partial time correlation functions of mass currents were calculated for the atoms belonging to the polar or the non-polar domains resulting from the heterogeneous structure of [C6C1im]Br. The partial correlation functions indicate that the polar domains are stiffer than the non-polar domains of the simulated ionic liquid.
采用分子动力学模拟研究了离子液体 1-己基-3-甲基咪唑溴化盐 [C6C1im]Br 的高频集体动力学。计算了几种波矢下的质量流涨落的时间相关函数，并在不同温度和压力下获得了纵向和横向声模激发的色散曲线 ω(k)。两种不同的热力学状态具有相同的高频声速，而与温度无关，只要它们具有相同的密度。针对来自 [C6C1im]Br 不均匀结构的极性或非极性畴，计算了质量流的部分时间相关函数。部分相关函数表明，极性畴比模拟离子液体的非极性畴更硬。
