TURBOMOLE Users Forum
TURBOMOLE Modules => Riper => Topic started by: kesha on April 02, 2020, 06:53:34 PM
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Hello,
I am getting started with using the riper module of Turbomole. I ran a few calculations from the Turbotest folder. The calculations worked fine when I ran riper with DFT but when I tried with HF, I see the following warning (pertaining to the HF exchange it seems):
+-------------------------------------------------------+
| !!!!!! WARNING !!!!!! |
+--------------------------------------------------------+
| |
| Your crystal is very small! |
| Better enlarge it, by using a larger |
| simulation box or increased number |
| of k-points. |
| Enlarge k-mesh or simulation cell! |
| |
+---------------------------------------------------------+
So, firstly, should I be bothered by this warning?
From the manual I understand how I can provide a k-point mesh and providing a large k-point mesh does help but when I am doing a Gamma point calculation, what is the way to enlarge the simulation cell since I don't need to provide a k-point mesh in that case? (For eg. I saw this warning with NaCl.3D.Gamma point calculation and MgO.3D SCF calculation which are given in the Turbotest folder)
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Hello,
which Turbomole version do you use? HF calculations for periodic systems using gamma point only are only meaningful for very large supercells. Otherwise you have to use k point sampling or your results will be simply wrong.
Please read the following paper for more information: https://pubs.acs.org/doi/10.1021/acs.jctc.8b00122
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Thank you for the information Prof. Sierka. That helps. I am using Turbomole version 7.4.