NEB question
Bernd Ensing
ensin... at gmail.com
Tue Mar 24 10:36:37 UTC 2015
Dear people,
I have three questions about a NEB calculation that I am running (see input
and output of first replica attached).
1) The number of replicas is 5, with the first and last replicas fixed.
Since the first replica is fixed (indeed the positions are constant in the
trajectory output), why is the wave function optimized after every NEB
geometry cycle? In the attached output the number of SCF cycles is more
than 1 (often more than 100 actually), even though the geometry has not
changed.
2) The number of processors per replica is 8, and I run on 2 nodes of 8
processors each. I see that on node 2, there is an Silver-BAND6.out (and
Silver-BAND2.out and Silver-BAND4.out) containing info of SCF cycles and
energies and so forth. What is this 6th output doing, considering that
there are only 5 replica's (there are only 5 trajectory outputs)? I was
hoping that cp2k would cycle all 5 replicas over the 2 nodes subsequently;
instead it puts replica's 1,3, and 5 on node 1, and 2, 4 and 6(???) on node
2. Is there a smarter way to use 2x8 procs on 5 replica's? (the system
does not really scale to 1x16 procs).
3) The number of SCF cycles is often more than 100 for all replicas. In
"normal" geometry optimization runs the number of SCF cycles is typically 7
to 15 (apart from the first round). Is this poor convergence in BAND normal
(due to the "stretched" geometries maybe?). Does anyone have advice on
this?
many thanks in advance.
Bernd
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&FORCE_EVAL
METHOD QS
&DFT
BASIS_SET_FILE_NAME /home/ensing/BASIS_SET/BASIS_COMBI
POTENTIAL_FILE_NAME /home/ensing/BASIS_SET/GTH_POTENTIALS
&MGRID
CUTOFF 280
NGRIDS 5
&END MGRID
&QS
METHOD GPW
EPS_DEFAULT 1.0E-12
&END QS
&SCF
MAX_SCF 100
EPS_SCF 5.0E-7
SCF_GUESS RESTART
&OUTER_SCF
EPS_SCF 1.0e-5
MAX_SCF 4
&END
&OT
MINIMIZER DIIS
N_DIIS 7
PRECONDITIONER FULL_ALL
ENERGY_GAP 0.001
&END
&END SCF
&XC
&XC_FUNCTIONAL PBE
&END XC_FUNCTIONAL
&VDW_POTENTIAL
DISPERSION_FUNCTIONAL PAIR_POTENTIAL
&PAIR_POTENTIAL
TYPE DFTD2
REFERENCE_FUNCTIONAL PBE
&END PAIR_POTENTIAL
&END VDW_POTENTIAL
&XC_GRID
XC_SMOOTH_RHO NN10
XC_DERIV SPLINE2_SMOOTH
&END XC_GRID
&END XC
&END DFT
&SUBSYS
&CELL
ABC 11.66 11.66 30.000
ALPHA_BETA_GAMMA 90.000 90.000 60.000
PERIODIC XYZ
&END CELL
&TOPOLOGY
COORDINATE XYZ
COORD_FILE replica1.xyz
&END TOPOLOGY
&KIND Ag
BASIS_SET DZVP-MOLOPT-SR-GTH-q11
POTENTIAL GTH-PBE-q11
&END KIND
&KIND H
BASIS_SET DZVP-GTH
POTENTIAL GTH-PBE-q1
&END KIND
&KIND C
BASIS_SET DZVP-GTH
POTENTIAL GTH-PBE-q4
&END KIND
&KIND O
BASIS_SET DZVP-GTH
POTENTIAL GTH-PBE-q6
&END KIND
&KIND Si
BASIS_SET DZVP-MOLOPT-SR-GTH-q4
POTENTIAL GTH-PBE-q4
&END KIND
&END SUBSYS
&END FORCE_EVAL
&GLOBAL
PROJECT test
RUN_TYPE BAND
PRINT_LEVEL LOW
PREFERRED_FFT_LIBRARY FFTSG
&END GLOBAL
&MOTION
&BAND
NPROC_REP 8
BAND_TYPE IT-NEB
NUMBER_OF_REPLICA 5
&OPTIMIZE_BAND
OPT_TYPE DIIS
&DIIS
&END
OPTIMIZE_END_POINTS FALSE
&END
&REPLICA
COORD_FILE_NAME replica1.xyz
&END
&REPLICA
COORD_FILE_NAME replica2.xyz
&END
&REPLICA
COORD_FILE_NAME replica3.xyz
&END
&REPLICA
COORD_FILE_NAME replica4.xyz
&END
&REPLICA
COORD_FILE_NAME replica5.xyz
&END
&PROGRAM_RUN_INFO HIGH
&END
&CONVERGENCE_INFO HIGH
&END
&REPLICA_INFO HIGH
&END
&END BAND
&CONSTRAINT
&FIXED_ATOMS
LIST 1..16
&END
&END CONSTRAINT
&GEO_OPT
MAX_ITER 100
&END
&PRINT
&TRAJECTORY
FORMAT XMOL
&EACH
GEO_OPT 1
&END
&END TRAJECTORY
&RESTART
&EACH
GEO_OPT 0
&END
ADD_LAST NUMERIC
&END RESTART
&END PRINT
&END MOTION
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