Hi all,
I'm considering running a handful of explicitly solvated (water) organic compound ab initio calculations in the presence of either a copper or zinc ion. I hope to find whether my compound sequesters the ion in question. My system is made up of 64 atoms: 6 O, 6 N, 18 C, the rest hydrogens. I aim to solvate between 8 to 16 water molecules, with either a single Zn or Cu. Already this is a relatively big system ab initio wise.
I've gone through dozens of manuscripts, all of which report several combinations of different function/basis-set pairs: from B3LYP, MP1-4, wb97xd, HF etc., and lanl2dz, 6-311++g(combination in here), and even DFT-U (which I have no experience with I'm afraid).
I understand some basis sets are selected according to what computational resources are at hand, that is to say an explicit split-valence or something with an electron core potential.
Any suggestions?
Many thanks
Hello Anthony,
An option could be OPBE or B3PW91 that should explain properly the metals. In general, hybrid dft should explain good the ion.
About basis set, (D,T)ZV should be work perfect in general.
I hope it helps you,
Joaquim
Hello Anthony,
for initial geometry optimization the B3LYP/Lanl2dz or PBE/Lanl2dz approach can be good. Then, you can refine the geometry with larger basis set, for example, 6-31G* or 6-31++G** (if polarization and diffuse functions on H's seem to be important, too). Generally, B3LYP should give good results for such a system. Hopefully it would be helpful, too.
Best regards,
Aleksey.
Hello Aleksey,
That is the exact same approach I have taken so far but I have also tried the wb97xd function. I am interested to see what differences I get when applying b3pw91/Def2SVP followed by Def2TVPP.
Mr. Nash,
Please find as attachment the accuracy of the discussed methods, including some other ones towards actinides (attachment ref. [1]). As it has been mentioned in this forum, the application of B3PW91 has yielded to generally meaningful results. The accuracy, predicting vibratioal properties is within 1 - 20 cm-1.
In addition to lanl2dz, I would to add sdd (attachment) as well as the reference [2] shown below, have provided information about the reliability of the data obtained.
[ref. 2] Lamshoft, M.; Storp, J.; Ivanova, B.; Spiteller, M. (2011)
Gas-phase CT-stabilized Ag(I) and Zn(II) metal-organic complexes–experimental vs. theoretical study, Polyhedron, 30, 2564
Particularly ref [2] is on ZnII and AgI complexes.