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0506nan木蟲(chóng) (小有名氣)
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[求助]
VASP中如何在體系中引入電子和空穴
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各位精通VASP的大蝦們,我剛看到一篇文獻(xiàn),關(guān)于在體系中引入電子和空穴的: Photoexcitation of electron hole pairs in titania results in charge separation, with electrons available to participate in the CO2 reduction. Here, we assume that the dynamics of charge separation is much faster than electron transfer to CO2; therefore the electrons available for reduction are thermalized to the bottom of TiO2 conduction band (CB), which is about 3.8 eV below the vacuum level.17 Photoexcited electrons are modeled by introduction of an extra electron into the system, which populates the conduction band of TiO2. The holes which compensate these electrons and interact with them electrostatically are modeled in three possible ways: (i) completely screened and having no influence (model I); (ii) positive background charge (model II); (iii) localized positive charge in the vicinity,modeled by a proton (model III). J. Phys. Chem. C 2010, 114, 21474–21481 這三個(gè)模型是怎么建的啊???VASP中可以同時(shí)引入電子和空穴嗎?好像MS中不可以!沒(méi)用過(guò)VASP,所以不明白這三個(gè)模型是怎么建的。 知道的請(qǐng)解釋一下,不勝感激!俺比較窮,懸賞10個(gè)金幣吧^_^ |
第一性原理 | VASP |

至尊木蟲(chóng) (職業(yè)作家)
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建議讀讀vasp手冊(cè)這一部分,以及這段所提到的文獻(xiàn): http://cms.mpi.univie.ac.at/vasp ... LDIPOL_EPSILON.html |
鐵桿木蟲(chóng) (著名寫(xiě)手)

鐵桿木蟲(chóng) (著名寫(xiě)手)
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這里只是加了一個(gè)多余的電子,并沒(méi)有空穴的引入下面這段話可以明顯的看出來(lái) TABLE 2: Calculated Adsorption Energies (in eV) of CO2 on Neutral Anatase (101) Surface Using Cluster and Periodic Models and on Negatively Charged Anatase (101) Surfaces Using the Cluster Model (I) and the Periodic Model (II) and H Reduced Anatase (101) Surface Using the Periodic Model (III) c |

至尊木蟲(chóng) (職業(yè)作家)
木蟲(chóng) (小有名氣)
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作者回復(fù):三種模型的建立。 A positive background charge is added automatically by VASP code if the number of electrons in the system is larger than total charge of atomic cores (see NELECT in the VASP manual) : http://cms.mpi.univie.ac.at/vasp/vasp/Index.html Model I is a cluster model, and extra electron does not need compensation (complete screening), model III has an extra proton which compensates the negative charge. Please keep in mind that these models are designed to study an extra electron, therefore the goal of introducing hole models is to see how their electrostatic potential influences this extra electron. |

木蟲(chóng) (小有名氣)

鐵桿木蟲(chóng) (著名寫(xiě)手)

木蟲(chóng) (小有名氣)
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模型1用的gaussian03,模型2和模型3用的VASP。 To account for the presence of an electron from photoexcitation, either an extra electron with a positive compensating background (model II) or one hydrogen atom adsorbed on the surface bridging O atom (model III) is introduced to populate the TiO2 conduction band. In the latter case, the electron from the hydrogen atom redistributes to the bottom of CB of TiO2 within self-consistent calculations leaving behind a proton mimicking a localized hole in terms of its Coulomb potential as long as it does not participate in reactions. In contrast, we consider the positive charge to be completely screened in our cluster calculations. |

木蟲(chóng) (小有名氣)

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看了樓主提供的文章的最后一段模型的敘述,加電子,空穴,是分別兩個(gè)不同的模型,并不是加完電子再加背景電荷吧 但是我也不知道怎么加入,在模型中加入電子或是質(zhì)子的話,是加在什么位置呢,還是指整個(gè)體系的 CASTEP在setup中有charge 的設(shè)定,不知道可不可以用這個(gè)設(shè)定 看了一些其他光催化的文章,如PHYSICAL REVIEW B 80, 235416 2009,計(jì)算方法部分對(duì)模型只是幾何結(jié)構(gòu)方面的描述,并沒(méi)有說(shuō)明電子和空穴的問(wèn)題,不知道是不是在模型建立的過(guò)程可以不用考慮? 最近也遇到了這個(gè)問(wèn)題,希望有同行解答 |
木蟲(chóng) (小有名氣)

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