Orca如何使用Engrad关键词计算CASSCF激发态梯度？

函数与激情

大家好，我想在orca里利用Engrad关键词计算casscf基态与激发态的能量以及梯度，我似乎没有在orca手册里找到casscf里指定态为感兴趣的态，是只能设置nroots吗？ 但是nroots=1与nroots=2计算出的梯度几乎一样啊，

另外Iroot关键词是针对TDDFT使用的关键词，我尝试在casscf模块加入Iroot关键词，似乎也不起作用。请问这该如何解决呢？

函数与激情

这个问题我在orca官方论坛提问了，大牛给了回复，虽然问题没解决，贴出地址给大家参考。 https://orcaforum.kofo.mpg.de/viewtopic.php?f=8&t=6146

Unfortunately, it is not as simple as in the TD-DFT case.
(in ORCA you a specific TD-DFT gradient via the IROOT command)

For CASSCF, if you do a state average calculation, your orbitals are only optimized for the average of all states that were included in the averaging. That means, that each individual state is not at a variational minimum and the regular CASSCF gradient equation does not apply. In this case one has to solve the CP-CASSCF equations to the get the state specific gradients. This comes at a significant extra cost. We are working on that. Hence, for the time being you cannot get what you want unless you manage to converge the CASSCF for each state individually.

Good luck!