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用基于密度泛函理论的第一性原理方法研究了Nb(110)表面氧原子覆盖度分别为0.25、0.50、0.75和1.00单层时对氧分子解离的影响.结果表明,在氧原子覆盖度不大于0.50单层时,由于氧分子和表面铌原子的较强相互作用,使它们能够自发解离.然而在氧原子覆盖度为0.75单层时,氧分子只能够在未占据的洞位附近解离,同时发生严重的晶格畸变.在形成一个氧原子单层后(1.00单层),氧分子只能弱吸附在Nb(100)表面上,此时氧原子向内扩散成为氧分子继续解离的速率决定步骤.这些结果从理论上解释了在形成一个氧原子单层后,Nb(110)表面氧分子吸收速率迅速下降的原因.
The first-principle method based on density functional theory (DFT) was used to study the effect of oxygen atoms on the dissociation of oxygen atoms when the coverage of oxygen atoms on the surface of Nb (110) was 0.25, 0.50, 0.75 and 1.00 respectively. When the monolayer is not greater than 0.50, oxygen molecules can spontaneously dissociate due to the stronger interaction between the oxygen molecules and the surface niobium atoms. However, when the oxygen atom coverage is 0.75 monolayer, the oxygen molecules can only move in the unoccupied holes And a serious lattice distortion occurs at the same time.On the formation of a single oxygen atom (1.00 monolayer), oxygen molecules can only weakly adsorb on the surface of Nb (100), at this time oxygen atoms diffuse inward into oxygen molecules Continue the rate-determining step of dissociation.These results theoretically explain the reason why the oxygen molecule absorption rate on the surface of Nb (110) decreases rapidly after the formation of an oxygen atom monolayer.