[CP2K-user] [CP2K:14133] MIX_CL_TRUNC + ADMM in cp2k development branch

august... at chem.uzh.ch august... at chem.uzh.ch
Mon Nov 2 10:27:10 UTC 2020

Dear Nicholas,

your XC input looks fine to me, but I have a few remarks. The cutoffs of the truncated Coulomb potential and the long range erf functions are very short. We typically use cutoffs that are around 6 Angstrom, which ensures that results are close enough to a calculation with standard Coulomb potential. Unless you are restarting your calculation from a well converged GGA level calculation, I would refrain from using the SCREEN_ON_INITIAL_P keyword, as the ATOMIC_GUESS starting point might not be good enough for porper screening. Finally, if you are using a range spearated HF potentials, you might want to combine it with a range separated DFT exchange functional as well.

I assume you set up the ADMM section properly and made a sensible choice of primary and auxiliary basis sets. Without your full input file however, this is impossible to say whether there is an issue there.

Hope this helps. Best, 

-----cp... at googlegroups.com wrote: -----
To: "cp2k" <cp... at googlegroups.com>
From: "Nicholas Winner" 
Sent by: cp... at googlegroups.com
Date: 10/28/2020 05:14PM
Subject: [CP2K:14133] MIX_CL_TRUNC + ADMM in cp2k development branch

Hello all,

I need to make use of range separated hybrid functionals for periodic systems, so I have pulled the latest development version of cp2k from github which adds this support to admm module (in hfx_admm_utils.F).

To the best of my knowledge, I have implemented it correctly, but the difference in final energy between PBE0 and MIX_CL_TRUNC is ~7 Ha, which seems rather large. When going from GGA -> PBE0 the energy difference <1 Ha. Obviously there should be some change when changing the interaction potential, but this has me considered.

GGA:  ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):             -983.840366364871670 PBE0 : ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):             -983.680119471562080
MIX_CL_TRUNC: ENERGY| Total FORCE_EVAL ( QS ) energy [a.u.]:    -974.290021294811368

Here is the XC section I am using to activate MIX_CL_TRUNC with ADMM. Can someone please sanity check and tell me if this is appropriate? 

                         &XC_FUNCTIONAL PBE
                                         PARAMETRIZATION ORIG
                                         SCALE_C 1
                                         SCALE_X 0.665 # 1 - alpha - beta
                                 &END PBE
                         &END XC_FUNCTIONAL
                                 FRACTION 1
                                         EPS_SCHWARZ 1e-07
                                         EPS_SCHWARZ_FORCES 1e-06
                                         SCREEN_ON_INITIAL_P True
                                         SCREEN_P_FORCES True
                                 &END SCREENING
                                         POTENTIAL_TYPE MIX_CL_TRUNC
                                         CUTOFF_RADIUS 1.8
                                         T_C_G_DATA t_c_g.dat
                                         SCALE_LONGRANGE 0.085 # alpha
                                         SCALE_COULOMB 0.25 # beta
                                         OMEGA 0.94486
                                 &END INTERACTION_POTENTIAL
                                         RANDOMIZE True
                                 &END LOAD_BALANCE
                                         EPS_STORAGE_SCALING 0.1
                                         MAX_MEMORY 2000
                                 &END MEMORY
                         &END HF
                 &END XC
Nicholas Winner  
 You received this message because you are subscribed to the Google Groups "cp2k" group.
 To unsubscribe from this group and stop receiving emails from it, send an email to cp... at googlegroups.com.
 To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/06e0d703-46a0-4e05-873a-3852d52f8d66n%40googlegroups.com.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20201102/1281b9a0/attachment.htm>

More information about the CP2K-user mailing list