基于密度泛函理论的第一性原理,采用Materials Studio 6.1软件的CASTEP模块对方解石的晶体结构及与水分子及水分子簇的吸附作用进行了研究.结果表明,方解石在参与化学反应时O的活性最强,C和Ca次之;其次确定了最稳定解离面为{1014}切面,...基于密度泛函理论的第一性原理,采用Materials Studio 6.1软件的CASTEP模块对方解石的晶体结构及与水分子及水分子簇的吸附作用进行了研究.结果表明,方解石在参与化学反应时O的活性最强,C和Ca次之;其次确定了最稳定解离面为{1014}切面,其Ca和O位点与单个水分子形成吸附,且与O位点吸附作用较强,H(H_2O)—O(CaCO_3)键与H(H_2O)—O(H_2O)键间形成氢键;{1014}切面水分子簇相互作用,水分子间及水分子与方解石表面均存在氢键作用,吸附发生在O位点和Ca位点,且主要发生在O位点.展开更多
Electronic structure, stability and bonding strength of a-Fe/WC interfaces between Ce-doped and undoped WC cermet coating were investigated by first-principles methodology based on densityfunctional theory(DFT). Based...Electronic structure, stability and bonding strength of a-Fe/WC interfaces between Ce-doped and undoped WC cermet coating were investigated by first-principles methodology based on densityfunctional theory(DFT). Based on the minimum mismatched lattices, the relatively stable interface that forms between WC(100) and bcc a-Fe(100) was employed to predict the atomic structure, bonding,and ideal work of adhesion. There are three possible positions which were defined as OT, MT, HCP, taking into account both C-and W-terminations. The sequence of structural stability tested in this paper was:MT > OT > HCP. After full relaxation, the results show that only the first and second layers of the interface have significant influence on the electronic structure between Fe and WC. The interaction of Ce elements at the interface is achieved by comparing the interface structure and electronic structure of the doped and undoped interfaces. Ce doped interface possesses a shorter interface distance(d0 = 0.09776 nm)and a larger interface energy(Wad = 8.98 J/m2) than undoped interface(Wad = 8.76 J/m2,d0= 0.10134 nm).Charge density distribution and difference, and density of states were utilized to characterize the electronic properties and determine the interfacial bonding.The results demonstrate that strong covalent bonding existed in the undoped interface, while a mixed covalent/ionic bonding was formed at the Ce-doped interface.展开更多
文摘基于密度泛函理论的第一性原理,采用Materials Studio 6.1软件的CASTEP模块对方解石的晶体结构及与水分子及水分子簇的吸附作用进行了研究.结果表明,方解石在参与化学反应时O的活性最强,C和Ca次之;其次确定了最稳定解离面为{1014}切面,其Ca和O位点与单个水分子形成吸附,且与O位点吸附作用较强,H(H_2O)—O(CaCO_3)键与H(H_2O)—O(H_2O)键间形成氢键;{1014}切面水分子簇相互作用,水分子间及水分子与方解石表面均存在氢键作用,吸附发生在O位点和Ca位点,且主要发生在O位点.
基金Project supported by National Natural Science Foundation of China(51505393)the National Key Research and Development Plan of China(2017YFB0305905)
文摘Electronic structure, stability and bonding strength of a-Fe/WC interfaces between Ce-doped and undoped WC cermet coating were investigated by first-principles methodology based on densityfunctional theory(DFT). Based on the minimum mismatched lattices, the relatively stable interface that forms between WC(100) and bcc a-Fe(100) was employed to predict the atomic structure, bonding,and ideal work of adhesion. There are three possible positions which were defined as OT, MT, HCP, taking into account both C-and W-terminations. The sequence of structural stability tested in this paper was:MT > OT > HCP. After full relaxation, the results show that only the first and second layers of the interface have significant influence on the electronic structure between Fe and WC. The interaction of Ce elements at the interface is achieved by comparing the interface structure and electronic structure of the doped and undoped interfaces. Ce doped interface possesses a shorter interface distance(d0 = 0.09776 nm)and a larger interface energy(Wad = 8.98 J/m2) than undoped interface(Wad = 8.76 J/m2,d0= 0.10134 nm).Charge density distribution and difference, and density of states were utilized to characterize the electronic properties and determine the interfacial bonding.The results demonstrate that strong covalent bonding existed in the undoped interface, while a mixed covalent/ionic bonding was formed at the Ce-doped interface.
