Li Hong, Mahanti S D, Pinnavaia Thomas J
Department of Physics and Astronomy and Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
J Phys Chem B. 2005 Nov 24;109(46):21908-14. doi: 10.1021/jp054106y.
The proton transfer process mediated by water molecules adsorbed in an aluminosilicate framework has been studied using ab initio molecular dynamics simulations. This investigation has been carried out using a quasi-one-dimensional model simulating the mesoporous aluminosilicate channel structures. The effects of both the water loading and temperature of the system have been considered. At low coverage (one water molecule per acid site), the hydroxonium ion (H(3)O)(+) is found to be a transition state, in agreement with earlier studies on zeolites. At a higher water coverage (two water molecules per acid site), the (H(5)O(2))(+) species and the hydrogen bonded "neutral complex" structure are both found to be stable complexes at finite temperatures. The vibrational frequency spectrum is simulated by performing a Fourier transform of the velocity autocorrelation function (VAF), and the peak positions in the VAF are compared with IR measurements and zero-temperature calculations.
利用从头算分子动力学模拟研究了吸附在铝硅酸盐骨架中的水分子介导的质子转移过程。这项研究是使用模拟介孔铝硅酸盐通道结构的准一维模型进行的。考虑了系统的水负载量和温度的影响。在低覆盖率（每个酸性位点一个水分子）下，发现水合氢离子（H(3)O）(+)是一个过渡态，这与早期对沸石的研究一致。在较高的水覆盖率（每个酸性位点两个水分子）下，发现（H(5)O(2)）(+)物种和氢键“中性复合物”结构在有限温度下都是稳定的复合物。通过对速度自相关函数（VAF）进行傅里叶变换来模拟振动频谱，并将VAF中的峰值位置与红外测量结果和零温度计算结果进行比较。
