简单量子化学问题答疑专帖

Vincentcanfly

之前所有的内容也没搞错呀，为啥会这样呢

乐平

贴这个报错编号有什么用……

要看输出文件（.out 文件）最后的报错信息

sobereva

Vincentcanfly 发表于 2024-6-29 20:46
之前所有的内容也没搞错呀，为啥会这样呢

看北京科音初级量子化学培训班（http://www.keinsci.com/workshop/KEQC_content.html）的ppt：

moiumuio

Hi everyone,
I want to calculate absorption and emission properties of a compound. Here is the step I am going to do
1. Opt freq b3lyp/6-311G** em=gd3bj
2. td cam-b3lyp/def2tzvp (from structure 1)
3. Opt freq td cam-b3lyp/6-311G** em=gd3bj
Is the procedure above logical? or do I have to change somewhere?
Thank you.

wzkchem5

moiumuio 发表于 2024-7-1 05:15
Hi everyone,
I want to calculate absorption and emission properties of a compound. Here is the step ...

The problem is that, while your absorption and emission wavelengths may be individually reasonably accurate, their difference (Stokes shift) is unreliable, since your absorption and emission calculations are done at different levels.
In general, for projects that involve both absorption and emission calculations, it is advisable (if not mandatory) to do the ground state and excited state geometry optimizations at the same level. If you want to calculate absorption wavelengths at a higher level of theory, you must use the same level of theory to recalculate the emission wavelength as well (but remember to turn on equilibrium solvation).

currywen

想请教下，经过Gaussian优化后，所呈现的结构图中展现的二面角能否用于文章中？是否有说服力。
谢谢

北大-陶豫

用GView 读这个键角没有问题，只要你优化用的方法是合理的就没问题

currywen

北大-陶豫 发表于 2024-7-1 15:43
用GView 读这个键角没有问题，只要你优化用的方法是合理的就没问题

好的，谢谢老师的答复。祝您生活愉快。

moiumuio

wzkchem5 发表于 2024-7-1 14:22
The problem is that, while your absorption and emission wavelengths may be individually reasonably ...

Thank you teacher,
Is it reasonable for me to use b3lyp-d3bj for optimization of excited state? or I have to use long-range corrected functionals?

wzkchem5

moiumuio 发表于 2024-7-1 13:21
Thank you teacher,
Is it reasonable for me to use b3lyp-d3bj for optimization of excited state? o ...

Without knowing the molecular structure it is impossible to tell. Generally, B3LYP-D3BJ is suitable for local excitation states, while CAM-B3LYP-D3BJ is suitable for charge transfer states, but both of the two rules have exceptions.

15670538028

老师好，我想分析一个分子的动态磁性（两个单电子），在跑完动力学轨迹中取点算Noodleman提出的耦合常数J时，三重态为基态，而对bs态进行单点计算能量时有相当一部分结果S^2为0，请问此时的能量结果可以作为公式中的Ebs项进行J的计算吗？    2， 取多个单点算出的耦合常数J相差很大（-1200 cm-1到2200cm-1),即使相邻两fs的耦合常数一个是 -1200cm-1,另一个为1750cm-1,请问这样的数据是不是异常，没有意义呢？

wzkchem5

15670538028 发表于 2024-7-2 03:25
老师好，我想分析一个分子的动态磁性（两个单电子），在跑完动力学轨迹中取点算Noodleman提出的耦合常数J时 ...

对BS态做稳定性分析了吗？

15670538028

wzkchem5 发表于 2024-7-2 15:39
对BS态做稳定性分析了吗？

稳定性分析通过stable=opt正在进行，结果还未出来，奇怪的是即使把这些BS态结果中S^2=0的点去掉，耦合常数J的动态变化也不是连续的，有很多跳点，不知这可能是什么原因呢？

moiumuio

wzkchem5 发表于 2024-7-1 23:38
Without knowing the molecular structure it is impossible to tell. Generally, B3LYP-D3BJ is suitabl ...

My structure includes conjugated polymers and a quencher to form a complex through pi-pi stacking. I want to figure out which quencher will cause charge transfer between those and the polymer. So in this case, do I have to use long-range corrected functionals?
Thank you

lurensan

各位老师好，请问IRC曲线走完有突出的点怎样处理（IRC正常结束，关键词irc=(rcfc,maxpoints=150,stepsize=20,lqa) 6-31g(d) scrf=(solvent=1,4-
dioxane) em=gd3 m062x guess=read geom=allcheck），要用图发文章