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zhangdi6802

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[交流] 【求助】高斯软件可以解决环境影响吗?

请教高手:高斯软件可以解决环境影响吗?比如某个分子在不同的溶剂中的结构以及相关的参数会发生变化,如何在实际环境中计算相关参数呢? 我的意思是此时的分子不是经典构型了。
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ccw531

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lei0736(金币+4,VIP+0):谢谢新人发言 十大“耐思”版主评选欢迎参与投票 http://edu.emuch.net/bbs/viewthread.php?tid=845527&fpage=1
I assume you are probably referring to solvent effects. Ideally, the rigorous ways to deal with solvent effects are carrying out QM calculations including solvent atoms ( by repeating the calculations for various orientations of solvent molecules and taking a sensible average over all calculations). This is, however, highly impractical.

The most common way to calculate solvent effects is to use a "continuum solvent model", where the molecular structure of the solvent is ignored, and the solvent is modeled as a continuous dielectric of an infinite external field that surrounds a cavity containing the solute molecule.  Methods for this approximation include:

The Quantum-Onsager Self-consistent reaction-field Method
The Multipole expansion method
The PCM (polarizable-continuum model) method

For more details, you may want to read an excellent textbook on quantum chemistry by I. N. Levine. "Quantum Chemistry", Fifth edition, Principle Hall, 2000. page 593.

Gaussian should be able to handle solvent effects. But, don't quote me on this. Some expertise is needed here.

[ Last edited by ccw531 on 2008-6-20 at 01:23 ]
2楼2008-06-20 01:17:34
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zhangsky8812

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lei0736(金币+3,VIP+0):谢谢新人发言 鼓励一个 十大“耐思”版主评选欢迎参与投票 http://edu.emuch.net/bbs/viewthread.php?tid=845527&fpage=1
implicit solvent model or explicit solvent model.

Both are used by different groups for different problems. Actually, we do not consider the solvent effects at first, and just carry out the calculations in vacuum. If the results are greatly deviating with the experimental results, we could add the PCM or CPCM to do the single-point calculations. If there's still some problems, do the PCM or CPCM optimizations. After the above modifications, there's still some possibilities that the calculating results could not explain the experimental results, then you need to use the explicit model.
3楼2008-06-20 04:11:53
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