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iamkz

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[交流] 【求助】无序固溶体建模及优化问题

请问通过MS建一个无序固溶体模型,尝试用VCA近似,是不是VCA近似时(是改变Compasition吧,不是Occupancy吧?),不能替换晶格上或面上的原子啊?只能替换晶格内的原子?
还有一个问题,若是想优化无序固溶体的结构,但在MS中建立的模型都是满足周期性边界条件(?),那就算用超胞对一个长程有序的体系其进行晶格优化,这样能模拟出真实的无序固溶体结构么?
谢谢
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iamkz

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fegg7502(金币+1,VIP+0):thank you very much! 11-2 20:35
引用回帖:
Originally posted by sars518 at 2009-11-2 14:33:



改变 composition  详细看看ms manual  有说明


无序,CPA 处理长程 较好

SC 也可以,不过可能要比较大

麻烦解释下CPA和SC,谢谢,我刚学没多久,看不太明白
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4楼2009-11-02 18:28:42
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B.C.Wang

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fegg7502(金币+1,VIP+0):thank you very much! 11-2 20:34
你可以把超晶格建大一些,包括的原子多一些。
2楼2009-11-02 07:44:41
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sars518

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qasd(金币+1,VIP+0):谢谢~ 11-2 19:51
引用回帖:
Originally posted by iamkz at 2009-11-1 22:11:
请问通过MS建一个无序固溶体模型,尝试用VCA近似,是不是VCA近似时(是改变Compasition吧,不是Occupancy吧?),不能替换晶格上或面上的原子啊?只能替换晶格内的原子?
还有一个问题,若是想优化无序固溶体的结 ...

改变 composition  详细看看ms manual  有说明


无序,CPA 处理长程 较好

SC 也可以,不过可能要比较大
人生是一场旅行,在欣赏风景的同时,别忘了你也是别人的风景。
3楼2009-11-02 14:33:03
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identation

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fegg7502(金币+0,VIP+0):错误答案 11-2 20:35
fegg7502(金币+0,VIP+0):你如果只改一个原子的成分的话,你这个原子到底是什么东西呢?,有没有真实的这类原子? 11-2 21:21
fegg7502(金币+4,VIP+0):鼓励讨论,收回我上次‘错误答案’评论,请大家讨论下再说吧,关于做合金跟掺杂的体系,以前有人这个问过我,我是持反对态度的,因为这个idea可以推广到一个极限去验证,假设一个氧化亚铁的晶胞吧,那意思是说你只要算一个原子(50%Fe,50% O)这样就简化了啊,但是你这样的话,如何确定晶胞参数呢? 11-2 22:09
fegg7502(金币+0,VIP+0):还有就是,是否存在这样一个含有(50%Fe,50% O)这样的一个粒子? 11-2 22:10
看说明,通过更改properties栏中的is mixture选项可以改原子组成。。。

About disorder
Disorder may be introduced into a structure in MS Modeling in one of two ways:

Mixture atoms may be used to simulate the case where one atomic site is randomly occupied by two or more different types of atom. MS Modeling allows you to create mixtures of different elements, oxidation states and isotopes.
Atom occupancy may be used to simulate vacancies which are randomly distributed through a structure.
Further information
Creating and editing mixture atoms
Changing atom occupancy
Dialogs for disorder

Creating and editing mixture atoms
Mixture atoms may be used to simulate the case where one atomic site is randomly occupied by two or more different types of atom. MS Modeling allows you to create mixtures of different elements, oxidation states and isotopes.

To edit the selected atoms as mixture atoms

Choose View | Explorers | Properties Explorer and select one or more atoms.
Double-click on the IsMixtureAtom property to display the Edit Mixture Atom dialog.
To edit a component of the mixture atom

Highlight the appropriate component in the list and click on the Edit button to display the Edit Mixture Component dialog.
To change the element type you may either type the element symbol directly into the box, select an element from the drop down list, or click the button to display the periodic table.
To change the isotope, select the desired mass number from the list of known isotope in the drop down list. Natural refers to the element having an isotopic mixture in naturally occurring abundances.
To change the composition, enter a value between 0.0 and 100.0 in the box. Note that the total composition of all components must add up to 100% and so it may be necessary to adjust the compositions of other components. MS Modeling will perform a scaling for you, but the results may be undesirable.
To change the oxidation state, enter the value between -5 and +8 in the box, or use the spin control.
To add a component to the mixture atom

Click the Add button to display the Edit Mixture Component dialog and follow steps 2-5 above.

To delete a component of the mixture atom

Select the component to be deleted in the list, and then click the Delete button.

[ Last edited by identation on 2009-11-2 at 21:07 ]
5楼2009-11-02 19:15:33
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