Dealing with Fe2+ in cp2k

[Lukas Krieger]

Dear all, I am a master student in physics and completely new to cp2k. I would like to perform an electronic structure calculation of heme in a quintuplet state (S=2). I then get the error "LSD: try to use a different multiplicity" and I assume that it is due to the fact that cp2k treats the Fe2+-ion in the centre of the heme group as a uncharged Fe-atom. Does someone know how to adjust the charge for the iron-ion and in worst case also the (partial) charges of the C, H, N and O-atoms inside the molecule so that cp2k takes the correct number of electrons?

Thanks in advance,

Lukas

[mdsimula...@gmail.com]

Can you submit your input?

[Matt Watkins]

Dear Lukas,

in DFT you cannot specify individual charges - they get assigned to the 'best' (lowest energy) locations. You can only specify the overall charge of the system and the multiplicity (S(S+!)) by the CHARGE and MULTIPLICITY keywords in the DFT section - if MULTIPLICITY is not 1 you need to also set UKS = .TRUE.

Matt

[Lukas Krieger]

Hi, sure.

[Lukas Krieger]

Dear Matt, thank you for your explanations. I'll try than the UKS= .TRUE option. One question still remains to me: How does DFT guarantee that the charges set according to lowest E locations are at the chemically right places as e.g. one negative charge on one oxygen of COO- and two positive ones on Fe2+?

Cheers,

Lukas

--
You received this message because you are subscribed to a topic in the Google Groups "cp2k" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/cp2k/R3d3eUC-OXs/unsubscribe.
To unsubscribe from this group and all its topics, send an email to cp2k+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/8c817eca-dc6f-4998-be3b-3e72cf068ae3n%40googlegroups.com.