[Pw_forum] 'etot_conv_thr' and 'forc_conv_thr' in the vc-relax calculation

[Shujun Hu]

Dear Drs,

I have some questions about the vc-relax calculation. I donnt know what is mean by
'etot_conv_thr' and 'forc_conv_thr' in the &CONTROL block of input file. Does
"forc_conv_thr" represent the force acting on the ions , or the "Total force"?
After a vc-relax calculation of ZnO, i found that "forc_conv_thr" has been
achieved in the middle of the calculation, but not the last 'it' (iteration). Also
the "etot_conv_thr", does it mean "!    total energy" in the general scf
calculation or the "Etot" appearing in the process of reconstruction the new
structure? And i found that these two values are different. Why? 
    Following is the output information during the calculation where i think
'forc_conv_thr' has been achieved ('etot_conv_thr' may be not. Because i do not
know what is mean.) and the input file.

    Best wishes

                              Shujun Hu


&&&&&&&&&&&&&&&&&&fragment of the outfiel&&&&&&&&&&&&&&&&&&&&&

     iteration #  3     ecut=    40.00 ryd     beta=0.70
     Davidson diagonalization (with overlap)
     ethr =  2.97E-09,  avg # of iterations =  3.0

     total cpu time spent up to now is    987.67 secs

     End of self-consistent calculation

!    total energy              =  -317.10170234 ryd
     estimated scf accuracy    <     0.00000002 ryd

     convergence has been achieved

     Forces acting on atoms (Ry/au):

     atom   1 type  1   force =     0.00000020   -0.00000044   -0.00010795
     atom   2 type  2   force =     0.00000028    0.00000022   -0.00002781
     atom   3 type  1   force =    -0.00000068    0.00000033    0.00010481
     atom   4 type  2   force =     0.00000020   -0.00000011    0.00003096

     Total force =     0.000156     Total SCF correction =     0.000710


     entering subroutine stress ...

          total   stress  (ryd/bohr**3)                  (kbar)     P=   -0.64
  -0.00001783  -0.00000002   0.00000000         -2.62      0.00      0.00
  -0.00000002  -0.00001778  -0.00000001          0.00     -2.62      0.00
   0.00000000  -0.00000001   0.00002266          0.00      0.00      3.33

     kinetic stress (kbar)  13774.50      0.00      0.00
                                0.00  13774.50      0.00
                                0.00      0.00  13795.05

     local   stress (kbar)    646.00     -0.13      0.03
                               -0.13    645.85      0.11
                                0.03      0.11  -1492.82

     nonloc. stress (kbar)   7199.63      0.00      0.00
                                0.00   7199.64      0.00
                                0.00      0.00   7192.88

     hartree stress (kbar)  17494.88      0.05     -0.01
                                0.05  17494.94     -0.04
                               -0.01     -0.04  18496.33

     exc-cor stress (kbar)  -7171.72      0.00      0.00
                                0.00  -7171.72      0.00
                                0.00      0.00  -7171.97

     corecor stress (kbar)      0.00      0.00      0.00
                                0.00      0.00      0.00
                                0.00      0.00      0.00

     ewald   stress (kbar) -31945.92      0.08     -0.02
                                0.08 -31945.82     -0.07
                               -0.02     -0.07 -30816.14

     hubbard stress (kbar)      0.00      0.00      0.00
                                0.00      0.00      0.00
                                0.00      0.00      0.00



     Entering Dynamics;  it =    11   time =  0.04840 pico-seconds

  new lattice vectors (alat unit) :
   0.999930641   0.000000053  -0.000000029
  -0.499965100   0.865964990  -0.000000011
  -0.000000046  -0.000000054   1.603075493
  new unit-cell volume =    333.8823 (a.u.)^3
  new positions in cryst coord
Zn       0.999979033   0.999979308   1.000277987
O        0.333311334   0.666643783   0.880471939
Zn       0.333323184   0.666651530   0.500187584
O        0.999989077   0.999984074   0.380882269
  new positions in cart coord (alat unit)
Zn       0.499954876   0.865947070   1.603521087
O       -0.000010450   0.577290146   1.411462971
Zn      -0.000002457   0.577296876   0.801838442
O        0.499962564   0.865951231   0.610582992

     Ekin =     0.00000146 Ryd   T =    0.2 K  Etot =  -317.10170088


&&&&&&&&&&&&&&&&&&fragment of the outfiel&&&&&&&&&&&&&&&&&&&&&

&&&&&&&&&&&&&&&&&&&&&&&&input file&&&&&&&&&&&&&&&&&&&&&&&&

 &CONTROL
                       title = zno ,
                 calculation = 'vc-relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = '/home/disk2/work/4.19/calculate_u/zno/new/temp/'
,
                  pseudo_dir = '/home/disk2/work/bin/PSEUDOPOTENTIAL/' ,
                      prefix = zno ,
                     disk_io = 'minimal' ,
                   verbosity = 'high' ,
                       nstep = 100 ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                          dt = 100 ,
                     tefield = .false. ,
 /
 &SYSTEM
                       ibrav = 4,
                   celldm(1) = 6.219036059,
                   celldm(3) = 1.602891754,
                         nat = 4,
                        ntyp = 2,
                     ecutwfc = 40 ,
                       nosym = .true. ,
                        nbnd = 25,
                 occupations = 'tetrahedra' ,
                     degauss = 0.005 ,
                    smearing = 'methfessel-paxton' ,
                       nspin = 1 ,
                  lda_plus_u = .false. ,
 /
 &ELECTRONS
            electron_maxstep = 500,
                 startingpot = 'atomic' ,
                 startingwfc = 'atomic' ,
                 mixing_mode = 'plain' ,
                 mixing_ndim = 20,
              diago_thr_init = 1.0E-7 ,
 /
 &IONS
                ion_dynamics = 'damp' ,
 /
 &CELL
               cell_dynamics = 'damp-w' ,
 /
ATOMIC_SPECIES
   Zn   65.38000  Zn.pbe-van.UPF 
    O   15.99900  O.pbe-rrkjus.UPF 
ATOMIC_POSITIONS angstrom 
   Zn      1.645450787    2.850004902    5.274845672    
    O     -0.000000677    1.900003430    4.650981508    
   Zn      0.000000241    1.900002591    2.637001887    
    O      1.645451454    2.850004118    2.015462269    
K_POINTS automatic 
  4 4 4   0 0 0 


&&&&&&&&&&&&&&&&&&&&&&&&input file&&&&&&&&&&&&&&&&&&&&&&&&