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tailor

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[交流] 【求助】siesta计算中,如何进行BSSE修正?

即基组重叠误差,全称为Basis Set Superposition Error(BSSE)。对于双分子A和B的相互作用能应该表述为E_interaction = E_AB - E_A - E_B + E_BSSE。第三项即为修正项。对于弱相互作用,E_BSSE所占E_interaction的比例往往不小,甚至超过它,如果不进行校正,可能正负号都不对。
      这些也是从网上查到的,但是网上主要介绍的都是高斯算法中的BSSE修正,由于本人用siesta算,想麻烦各位高手多多赐教!!
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tailor

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zxzj05(金币+1):谢谢回帖交流 2010-09-25 22:34:07
引用回帖:
Originally posted by zhangguangping at 2010-09-06 21:30:41:

为什么要算这个?什么体系才学要考虑BSSE修正啊?
我不是很懂,但是对你的问题很感兴趣,想问问你。

What we calculated is the Basis Set Superposition Error (BSSE) that is an error occurring when you use a finite basis set to study, for example, a chemical reaction. In a tipical reaction you calculate the electronic structure of the reactants separately, let us say A and B, and then the electronic structure of the product, A+B. What happens in this case is that you are using different basis sets to represent the reactants in each step of the calculation. When you calculate the isolated reactant A, you use the basis set of A, and the electrons of A will be arranged spatially on these provided orbitals. However, when you put both systems together in the A+B, the electrons of A will have now a greater spatial freedom, since they can now occupy orbitals coming from B. The same happens with B. You have different basis sets to distribute the electrons of A in the two situations.
To correct this, you need to recalculate the energy of the isolated reactants (A and B) by considering the basis set of both reactants, i.e., the calculations of the isolated reactant A will now include the basis sets of B (without the system B itself). It needs to be done for each configuration that you take into account in the reaction of A+B. Now you will have the same basis set for the isolated reactants and the product.
You can look for more information searching for "counterpoise correction"
5楼2010-09-10 19:36:33
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