[CP2K-user] [CP2K:16243] Improve extrapolation between relaxation steps?

Nicholas Winner nwinner at berkeley.edu
Tue Nov 16 17:58:59 UTC 2021

Hello all, 

When I run a relaxation for a complex system, e.g. in my case a defective 
transition metal oxide with hybrid dft on a modest ~200 atom supercell, 
each SCF still takes quite a long time to converge. 

I originally came from vasp before switching to cp2k, and it in that code, 
my experience was that once the first scf loop converged, the next 
relaxation step would take much less time, and so on until the last few 
steps converged in just a few iterations. This isn't my experience with 
CP2K though. Running CG on my most recent relaxation I still find that 
after more than 20 relaxation steps, 40-50 scf steps are required to 
achieve convergence.

Is this something that I could improve by changing certain settings? Below 
is the relevant info for my input file. Please note that I understand 
FULL_KINETIC and CG might lead to slower convergence than FULL_ALL + DIIS, 
but my question lies in why convergence is not appreciably speeding up 
rather than its absolute speed.








                UKS T

                MULTIPLICITY 0

                CHARGE 4


                        MAX_ITER_LUMO 400

                        MAX_SCF 50

                        EPS_SCF 1e-06

                        SCF_GUESS RESTART


                                ALGORITHM STRICT

                                MINIMIZER CG

                                LINESEARCH 2PNT

                                PRECONDITIONER FULL_KINETIC

                                ENERGY_GAP 0.01

                                ROTATION F

                                OCCUPATION_PRECONDITIONER F

                        &END OT


                                EPS_SCF 1e-06

                                MAX_SCF 20

                        &END OUTER_SCF

                &END SCF


                        ADMM_PURIFICATION_METHOD None

                        METHOD BASIS_PROJECTION



                        EPS_DEFAULT 1e-12

                        EPS_PGF_ORB 1e-16

                        EXTRAPOLATION PS

                        METHOD GPW

                &END QS


                        NGRIDS 5

                        CUTOFF 550.0

                        REL_CUTOFF 50.0

                &END MGRID


                        &XC_FUNCTIONAL NO_SHORTCUT


                                        SCALE_X 0.0

                                        SCALE_C 1.0

                                &END PBE


                                        SCALE_X 0.063

                                        SCALE_X0 0.877

                                        OMEGA 0.07

                                &END XWPBE


                                        SCALE_X 0.123

                                        CUTOFF_RADIUS 5.930000000000001

                                &END PBE_HOLE_T_C_LR

                        &END XC_FUNCTIONAL


                                FRACTION 1.0


                                        EPS_SCHWARZ 1e-07

                                        EPS_SCHWARZ_FORCES 1e-06

                                        SCREEN_P_FORCES T

                                        SCREEN_ON_INITIAL_P T

                                &END SCREENING


                                        POTENTIAL_TYPE MIX_CL_TRUNC

                                        OMEGA 0.07

                                        SCALE_COULOMB 0.06

                                        SCALE_LONGRANGE 0.063

                                        CUTOFF_RADIUS 5.930000000000001

                                        T_C_G_DATA t_c_g.dat

                                &END INTERACTION_POTENTIAL


                                        RANDOMIZE T

                                &END LOAD_BALANCE


                                        EPS_STORAGE_SCALING 0.1

                                        MAX_MEMORY 2000

                                &END MEMORY

                        &END HF

                &END XC


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