Li2SO4溶液中离子间的缔合相互作用:基于密度泛函理论和分子动力学模拟的研究

摘要

基于密度泛函理论,使用B3LYP/aVDZ方法对[Li2SO4(H2O) n]0(n=0～10、18)水合团簇的结构和性质进行了系统地研究,并结合Car-Parrinello分子动力学(CPMD)模拟了不同浓度的Li2SO4溶液结构,目的在于理解在Li2SO4溶液中离子间缔合相互作用及可能存在的物种.研究发现,对于[Li2SO4(H2O) n]0(n=0～10、18)水合团簇,双配位单齿螯合接触离子对结构比双配位双齿螯合接触离子对结构更稳定,溶剂共享离子对结构最不稳定.同时,CPMD模拟结果表明,在3.09和3.17 mol/kg的Li2SO4溶液中,双配位单齿螯合接触离子对结构仍然是主要物种.以上结果表明在饱和的Li2SO4溶液(3.16 mol/kg)中,Li+和SO2-4 离子间的相互缔合作用主要以双配位单齿螯合接触离子对结构的物种存在,而具有双配位双齿螯合离子对结构的物种占少数,溶剂共享离子对结构几乎不存在.%In this paper,the structures and properties of [Li2SO4(H2O) n]0(n=0～10,18) hydrated clusters are systematically investigated by B3LYP/aVDZ methods based on density functional theory to understand the ion-associated interactions and the main species in Li2SO4aqueous solution. Meanwhile,the Li2SO4aqueous solutions in different concentrations are also studied by using Car-Parrinello molecular dynamics(CPMD) simulation.It is noted that bis-bidentate contact ion pairs are less stable than bis-monodendate contact ion pairs for [Li2SO4(H2O) n]0(n=0～10,18) clusters,and the solvent-shared ion pairs are the least stable structures. The CPMD simulation results show that bis-monodendate contact ion pairs are the main species in 3.09 and 3. 17 mol/kg Li2SO4aqueous solutions. It could be considered that the ions-associated interaction between Li+and SO2-4 exists mainly as bis-monodendate contact ion pairs in saturated Li2SO4aqueous solution (3.16 mol/kg),while bis-bidentate contact ion pairs are of minority,solvent-shared ion pairs can be almost neglected.