Temp control problem, OT convergence problem, Langevin dynamics SGCPMD
Bouzid Assil
assil... at gmail.com
Wed Nov 5 09:50:30 UTC 2014
Dear CP2k users,
I am using cp2k to perform MD simulations based on the second generation
Car-Parrinello MD (Kühne scheme). I have started by a small binary
chalcogenide system that I have already generated using the standard CPMD.
As a first step I want to relax my system at 0K using the ANNEALING
procedure, this is supposed to reduce the forces acting between the "atoms"
at each MD step by a given factor (say 0.9). To control the situation I
have used at first gamma_D = 0.0000. My problem is that after more than
30ps the temperature stabilize around 1000K and won't go down. I have also
tried an NVT run at 300K using the NOSE HOOVER thermostat but no way, the
thermostat is not able to control the temperature (I have tried different
TIMECON values, always the same behaviour!).
When analysing the output files, there is a common strange thing between
all these runs (and also an other run on water molecules), when performing
the SCF WAVEFUNCTION OPTIMIZATION typically the convergence is reached
after 2 iterations of the outer SCF loop BUT after the first ~10 MD steps
the convergence is not reached at all and only 2 OT steps are performed! is
this normal (for sure no!) but why it happens then?!
* here is an example of output: *
----------------------------------- OT
---------------------------------------
Allowing for rotations: F
Optimizing orbital energies: F
Minimizer : DIIS : direct inversion
in the iterative subspace
using : - 7 DIIS vectors
- safer DIIS on
Preconditioner : FULL_KINETIC : cholesky inversion of T + eS
Precond_solver : DEFAULT
stepsize : 0.08750000
energy_gap : 0.00200000
eps_taylor : 0.10000E-15
max_taylor : 4
mixed_precision : F
----------------------------------- OT
---------------------------------------
Step Update method Time Convergence Total energy
Change
------------------------------------------------------------------------------
1 OT DIIS 0.87E-01 2.1 0.00000982 -906.5667899239
-9.07E+02
2 OT DIIS 0.87E-01 2.5 0.00000932 -906.5667939977
-4.07E-06
*** SCF run NOT converged ***
Electronic density on regular grids: -640.0000000000
-0.0000000000
Core density on regular grids: 639.9999999985
-0.0000000015
Total charge density on r-space grids: -0.0000000015
Total charge density g-space grids: -0.0000000015
Overlap energy of the core charge distribution:
0.00000056633200
Self energy of the core charge distribution:
-1927.34045098667070
Core Hamiltonian energy:
434.65748894621680
Hartree energy:
790.75025229030484
Exchange-correlation energy:
-204.63408481387373
Total energy:
-906.56679399769098
ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):
-906.566801465010712
*******************************************************************************
ENSEMBLE TYPE =
LANGEVIN
STEP NUMBER =
34788
TIME [fs] =
34788.000000
CONSERVED QUANTITY [hartree] =
-0.906018037069E+03
INSTANTANEOUS
AVERAGES
CPU TIME [s] = 9.85
9.56
ENERGY DRIFT PER ATOM [K] = -0.352815792553E+06
-0.346958228435E+06
POTENTIAL ENERGY[hartree] = -0.906566801465E+03
-0.906008788692E+03
KINETIC ENERGY [hartree] = 0.548764395757E+00
0.221663346691E+01
TEMPERATURE [K] = 970.789
3921.326
*******************************************************************************
*Here is a part of my input file:*
&MOTION
&MD
ENSEMBLE LANGEVIN
STEPS 15000
ANNEALING 0.8
TIMESTEP 1.0
&LANGEVIN
GAMMA 0.0001
NOISY_GAMMA 0.000
&END LANGEVIN
&END MD
&PRINT
&RESTART
&EACH
MD 1
&END EACH
BACKUP_COPIES 3
&END RESTART
&END PRINT
&END MOTION
&FORCE_EVAL
METHOD QUICKSTEP
&DFT
BASIS_SET_FILE_NAME BASIS_MOLOPT
POTENTIAL_FILE_NAME GTH_POTENTIALS
WFN_RESTART_FILE_NAME meta-RESTART.wfn
&MGRID
&RS_GRID
DISTRIBUTION_TYPE REPLICATED
&END RS_GRID
CUTOFF 300
&END MGRID
&PRINT
&DFT_CONTROL_PARAMETERS
&END DFT_CONTROL_PARAMETERS
&END PRINT
&QS
EPS_DEFAULT 1.0e-12
EXTRAPOLATION ASPC
EXTRAPOLATION_ORDER 3
MAP_CONSISTENT TRUE
&END QS
&SCF
EPS_SCF 1.0e-7
MAX_SCF 50
MAX_SCF_HIST 2
&OT ON
MINIMIZER DIIS
PRECONDITIONER FULL_KINETIC
ENERGY_GAP 0.002
STEPSIZE 0.0875
&END OT
&OUTER_SCF ON
MAX_SCF 100
EPS_SCF 1.0e-7
&END OUTER_SCF
Any input on the possible origin of this problem is highly appreciated!
Many thanks.
All the best,
Assil Bouzid
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