He C, Lian J S, Jiang Q
Key Laboratory of Automobile Materials, Ministry of Education, Changchun 130025, China.
J Phys Chem B. 2005 Oct 27;109(42):19893-6. doi: 10.1021/jp0531558.
Electronic structures of hexagonal ice (ice Ih), high-density amorphous ice (HDA), and very high-density amorphous ice (VHDA) are investigated using ab initio density functional theory (DFT) at 77 K under a pressure of 0.1 MPa, focusing on band structure, density of states (DOS), partial density of states (PDOS), and electron density. It is found that the integration intensity of the O-2p bonding band in HDA is 1.53 eV wider than that in the VHDA. Because more 2p electrons in HDA participate the 2p-1s hybridization of O-H. The classical molecular dynamics (MD) method has further been carried out to analyze the hydrogen bond network of HDA and VHDA with larger numbers of water molecules under the same temperature, pressure, and boundary conditions used as those during the DFT calculation. MD results show that there exists some water molecules with five hydrogen bonds in both HDA (4.1 +/- 0.1%) and VHDA (2.8 +/- 0.1%), as compared with the LDA, being consistent with the integration intensity results of PDOS. This result can be used to interpret the physical nature of the similar transition temperature of HDA and VHDA to LDA with different heating rates.
在0.1MPa压力和77K温度下，利用从头算密度泛函理论（DFT）研究了六方冰（冰Ih）、高密度非晶冰（HDA）和极高密度非晶冰（VHDA）的电子结构，重点关注能带结构、态密度（DOS）、分态密度（PDOS）和电子密度。研究发现，HDA中O-2p成键带的积分强度比VHDA中的宽1.53eV。这是因为HDA中有更多的2p电子参与了O-H的2p-1s杂化。进一步采用经典分子动力学（MD）方法，在与DFT计算相同的温度、压力和边界条件下，分析了含有更多水分子的HDA和VHDA的氢键网络。MD结果表明，与低密度非晶冰（LDA）相比，HDA（4.1±0.1%）和VHDA（2.8±0.1%）中都存在一些具有五个氢键的水分子，这与PDOS的积分强度结果一致。该结果可用于解释HDA和VHDA在不同加热速率下向LDA转变时相似转变温度的物理本质。
