[Pw_forum] vc_relax convergence criteria

[Timothy Mason]

Group,

I find that vc_relax appears to have differente convergence criteria depending on which algorithm I use.   why is this?   both output files reveal the same forces on every atom after the first scf run.   

the following control inputs and following cell parameters are considered converged for BFGS but not for damp-w.   input file is provided below as are the force and stress results of the first scf run.  The only difference between the other input file is that ion_Dynanics and cell dynamics are replaced with 'bfgs'.  

thanks,

Tim Mason : graduate student , university of missouri st. louis



&CONTROL
calculation = "vc-relax",
prefix = 'n9_cont',
tprnfor = .TRUE.
pseudo_dir = '/home/thmmqc/pwscf/psps/US_GGA',
outdir='/home/thmmqc/tmp'
etot_conv_thr = 1.0D-8
forc_conv_thr = 0.001,
dt =30
nstep = 100
/

&SYSTEM
ibrav = 0, nat = 15, ntyp = 5,
ecutwfc = 40
ecutrho = 480
celldm(1) = 1.889725989
/

&ELECTRONS
mixing_mode = 'plain',
mixing_beta = 0.7,
conv_thr = 1.0D-10,
/

&IONS
ion_dynamics  = 'damp',
ion_damping  = 0.5,
ion_positions = 'from_input',
pot_extrapolation = "second_order",
wfc_extrapolation = "second_order",
upscale = 100,
/

&CELL
cell_dynamics = "damp-w",
press = 0.0,

/

ATOMIC_SPECIES
Li 1.0 Li.pbe-n-van.UPF
Ca 1.0 Ca.pbe-nsp-van.UPF
N 1.0 N.pbe-rrkjus.UPF
H 1.0 H.pbe-rrkjus.UPF
B 1.0 B.pbe-n-van.UPF

CELL_PARAMETERS
6.04984441 0.07947561 0.15763675 
-1.73979839 9.57714512 0.75491312 
-1.44861278 4.74878467 5.48694513 

ATOMIC_POSITIONS {crystal}
Li 0.520452827000 -0.010315542000 1.409909233000 
Ca 0.695778370000 0.477023050000 -0.049490890000 
 N 0.431958544000 0.703293048000 0.694429814000 
 H 0.318686095000 0.666672029000 0.612147697000 
 H 0.335911859000 0.689088529000 0.810462743000 
 H 0.360709987000 0.300964023000 0.638729658000 
 H 0.201482918000 0.495572043000 0.343835757000 
 H 0.128550349000 0.243802563000 0.512226432000 
 H 0.079408634000 0.326602576000 0.652481493000 
 H 0.849854970000 0.835524836000 -0.001662989000 
 H 0.744851787000 0.657416041000 0.317036490000 
 H 0.808377359000 0.910829253000 0.149232970000 
 H 0.571308073000 0.847867969000 0.035708674000 
 B 0.192474730000 0.341596546000 0.537027123000 
 B 0.743409823000 0.812482642000 0.125603330000 

K_POINTS automatic
4 4 4 0 0 0

************forces/stresses**************

     Forces acting on atoms (Ry/au):


     negative rho (up, down):  0.141E-03 0.000E+00
     atom   1 type  1   force =    -0.00003810   -0.00012386 0.00011116
     atom   2 type  2   force =    -0.00001862   -0.00011006 0.00011622
     atom   3 type  3   force =    -0.00013613    0.00018277 0.00037626
     atom   4 type  4   force =    -0.00018482   -0.00013005 0.00033089
     atom   5 type  4   force =     0.00014399   -0.00018545 0.00010084
     atom   6 type  4   force =    -0.00033470   -0.00009963 0.00013277
     atom   7 type  4   force =    -0.00001692    0.00010745 0.00044525
     atom   8 type  4   force =     0.00014860    0.00054225 0.00007950
     atom   9 type  4   force =     0.00004670   -0.00009161 0.00021222
     atom  10 type  4   force =    -0.00004822    0.00001277 0.00020842
     atom  11 type  4   force =     0.00017014   -0.00020814 0.00004839
     atom  12 type  4   force =     0.00007402    0.00019658 0.00009918
     atom  13 type  4   force =    -0.00036718   -0.00001416 0.00022673
     atom  14 type  5   force =     0.00006543    0.00025720 0.00043955
     atom  15 type  5   force =     0.00049580   -0.00033607 0.00017440

     Total force =     0.001489     Total SCF correction =     0.000015


     entering subroutine stress ...


     negative rho (up, down):  0.141E-03 0.000E+00
          total   stress  (Ry/bohr**3)         (kbar)     P=    1.59
   0.00000309   0.00000387   0.00000120       0.45      0.57      0.18
   0.00000387   0.00001595   0.00000723       0.57      2.35      1.06
   0.00000120   0.00000723   0.00001333       0.18      1.06      1.96