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events:2018_summer_school:scf_setup

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Sensible SCF setups

http://www.cp2k.org

SCF

The Kohn-Sham equations are non-linear. The potential changes as we optimise the Molecular Orbitals.

In this exercise we will explore a few of the options available to get a fast and robust optimisation for most systems.

Traditional Diagonalisation (TD)

Here is a basic input for a periodic box of water including a SCF section suitable for TD:

scf_basic.inp
&FORCE_EVAL
  METHOD QS
  &DFT
    BASIS_SET_FILE_NAME GTH_BASIS_SETS
    BASIS_SET_FILE_NAME BASIS_MOLOPT
    POTENTIAL_FILE_NAME POTENTIAL
    &MGRID
      CUTOFF 300
    &END MGRID
    &QS
      EPS_DEFAULT 1.0E-12
    &END QS
    &SCF
      SCF_GUESS ATOMIC
    # SCF_GUESS        RESTART
      EPS_SCF      1.0E-5
      &MIXING
        ALPHA 0.4
      &END
    &END SCF
    &XC
      &XC_FUNCTIONAL Pade
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &CELL
      ABC 9.8528 9.8528 9.8528
    &END CELL
   # 32 H2O (TIP5P,1bar,300K) a = 9.8528
    &COORD
   O       2.280398       9.146539       5.088696
   O       1.251703       2.406261       7.769908
   O       1.596302       6.920128       0.656695
   O       2.957518       3.771868       1.877387
   O       0.228972       5.884026       6.532308
   O       9.023431       6.119654       0.092451
   O       7.256289       8.493641       5.772041
   O       5.090422       9.467016       0.743177
   O       6.330888       7.363471       3.747750
   O       7.763819       8.349367       9.279457
   O       8.280798       3.837153       5.799282
   O       8.878250       2.025797       1.664102
   O       9.160372       0.285100       6.871004
   O       4.962043       4.134437       0.173376
   O       2.802896       8.690383       2.435952
   O       9.123223       3.549232       8.876721
   O       1.453702       1.402538       2.358278
   O       6.536550       1.146790       7.609732
   O       2.766709       0.881503       9.544263
   O       0.856426       2.075964       5.010625
   O       6.386036       1.918950       0.242690
   O       2.733023       4.452756       5.850203
   O       4.600039       9.254314       6.575944
   O       3.665373       6.210561       3.158420
   O       3.371648       6.925594       7.476036
   O       5.287920       3.270653       6.155080
   O       5.225237       6.959594       9.582991
   O       0.846293       5.595877       3.820630
   O       9.785620       8.164617       3.657879
   O       8.509982       4.430362       2.679946
   O       1.337625       8.580920       8.272484
   O       8.054437       9.221335       1.991376
   H       1.762019       9.820429       5.528454
   H       3.095987       9.107088       5.588186
   H       0.554129       2.982634       8.082024
   H       1.771257       2.954779       7.182181
   H       2.112148       6.126321       0.798136
   H       1.776389       7.463264       1.424030
   H       3.754249       3.824017       1.349436
   H       3.010580       4.524142       2.466878
   H       0.939475       5.243834       6.571945
   H       0.515723       6.520548       5.877445
   H       9.852960       6.490366       0.393593
   H       8.556008       6.860063      -0.294256
   H       7.886607       7.941321       6.234506
   H       7.793855       9.141028       5.315813
   H       4.467366       9.971162       0.219851
   H       5.758685      10.102795       0.998994
   H       6.652693       7.917443       3.036562
   H       6.711966       7.743594       4.539279
   H       7.751955       8.745180      10.150905
   H       7.829208       9.092212       8.679343
   H       8.312540       3.218330       6.528858
   H       8.508855       4.680699       6.189990
   H       9.742249       1.704975       1.922581
   H       8.799060       2.876412       2.095861
   H       9.505360       1.161677       6.701213
   H       9.920117      -0.219794       7.161006
   H       4.749903       4.186003      -0.758595
   H       5.248010       5.018415       0.403676
   H       3.576065       9.078451       2.026264
   H       2.720238       9.146974       3.273164
   H       9.085561       4.493058       9.031660
   H       9.215391       3.166305       9.749133
   H       1.999705       2.060411       1.927796
   H       1.824184       0.564565       2.081195
   H       7.430334       0.849764       7.438978
   H       6.576029       1.537017       8.482885
   H       2.415851       1.576460       8.987338
   H       2.276957       0.099537       9.289499
   H       1.160987       1.818023       4.140602
   H       0.350256       2.874437       4.860741
   H       5.768804       2.638450       0.375264
   H       7.221823       2.257514       0.563730
   H       3.260797       5.243390       5.962382
   H       3.347848       3.732214       5.988196  
   H       5.328688       9.073059       5.982269
   H       5.007063       9.672150       7.334875
   H       4.566850       6.413356       3.408312
   H       3.273115       7.061666       2.963521
   H       3.878372       7.435003       6.843607
   H       3.884673       6.966316       8.283117
   H       5.918240       3.116802       5.451335
   H       5.355924       2.495093       6.711958
   H       5.071858       7.687254      10.185667
   H       6.106394       7.112302       9.241707
   H       1.637363       5.184910       4.169264
   H       0.427645       4.908936       3.301903
   H       9.971698       7.227076       3.709104
   H      10.647901       8.579244       3.629806
   H       8.046808       5.126383       2.213838
   H       7.995317       4.290074       3.474723
   H       1.872601       7.864672       7.930401
   H       0.837635       8.186808       8.987268
   H       8.314696      10.115534       2.212519
   H       8.687134       8.667252       2.448452
    &END COORD
    &KIND H
      BASIS_SET DZVP-GTH
      POTENTIAL GTH-PADE-q1
    &END KIND
    &KIND O
      BASIS_SET DZVP-GTH
      POTENTIAL GTH-PADE-q6
    &END KIND
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT H2O-32
  RUN_TYPE MD
  PRINT_LEVEL MEDIUM
&END GLOBAL
TASK This uses a rather small BASIS_SET DVZP-GTH which is much too small for production runs.

Repeat the calculation using 

BASIS_SET TZV2P-GTH
BASIS_SET DZVP-MOLOPT-GTH
BASIS_SET TZV2P-MOLOPT-GTH

You should change the basis set for each atomic type (kind) in each case.

Orbital Transformation (OT)

We can see the effect of changing to the OT method by simply changing the SCF section. 

&SCF
  SCF_GUESS ATOMIC
  EPS_SCF 1.0E-06
  MAX_SCF 20
  &OT ON
    MINIMIZER DIIS
    PRECONDITIONER FULL_ALL
    ENERGY_GAP 0.001
  &END OT
  &OUTER_SCF
    MAX_SCF 2
  &END OUTER_SCF
&END SCF
TASK See how OT compares with TD for the different basis sets.
events/2018_summer_school/scf_setup.1529227430.txt.gz · Last modified: 2020/08/21 10:14 (external edit)