Eigen-values not converged, warning in Quantum espresso

Question

I am running a simple example of vc-relax/scf for aluminum using PBE pseudo-potential.Setting are given below

 &control                                                            
    calculation='vc-relax'                                           
    restart_mode='from_scratch',                                     
    pseudo_dir =.                                                    
    outdir=./tmp/,                                                   
    prefix='al'                                                      
    tprnfor = .true.                                                 
    tstress = .true.                                                 
    etot_conv_thr=1D-06                                              
    forc_conv_thr=1D-03                                              
 /                                                                   
 &system                                                             
    ibrav=  2,A=4.04,nat=  1, ntyp= 1, ecutwfc =30.0,                
    occupations='smearing', smearing='mp', degauss=0.05              
 /                                                                   
 &electrons                                                          
  conv_thr    = 1.D-6,                                               
  mixing_mode='plain',                                               
  startingwfc='atomic-random',                                              
  mixing_beta = 0.7D0,                                               
  diagonalization = "cg"                                             
 /                                                                   
&ions                                                                
ion_dynamics='bfgs'                                                  
/                                                                    
&cell                                                                
cell_dynamics='bfgs'                                                 
/                                                                    
                                                                     
ATOMIC_SPECIES                                                       
 Al  26.98 Al.pbe-n-kjpaw_psl.1.0.0.UPF                              
ATOMIC_POSITIONS alat                                                
 Al 0.00 0.00 0.00                                                   
K_POINTS automatic
21 21 21 0 0 0

I am getting warning in some of the scf cycle as

     iteration #  1     ecut=    30.00 Ry     beta= 0.70
     CG style diagonalization
     c_bands:  1 eigenvalues not converged
     c_bands:  5 eigenvalues not converged
     c_bands:  3 eigenvalues not converged
     c_bands:  2 eigenvalues not converged
     c_bands:  4 eigenvalues not converged
     c_bands:  3 eigenvalues not converged
     c_bands:  3 eigenvalues not converged
     c_bands:  4 eigenvalues not converged
     c_bands:  4 eigenvalues not converged

I have changed mixing_mode,mixing_beta,Kpoints,ecutwfc,smearing startingwfc,diagonalization and convergence tolerances, to all extent but warning still exists. What is perfect solution to this warning?

Answer 1

Please go through the userguide. At the bottom, it has some nice suggestions. Check this mail thread also.

Does the program stops because too many errors have not converged or, the calculation keeps going on ?

If the calculation did not stop and keeps going on, then you can ignore these warnings. Please do some convergence tests before you proceed for vc-relax. I did calculations for Al, I even got convergence error in first iteration but subsequent calculations were fine.

[Al.vc-relax.in]

 &CONTROL
                 calculation = 'vc-relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = '.' ,
                  pseudo_dir = '.' ,
                      prefix = 'Al' ,
 /
 &SYSTEM
                       ibrav = 2,
                   celldm(1) = 7.6897,
                         nat = 1,
                        ntyp = 1,
                     ecutwfc = 80 ,
                 occupations = 'smearing' ,
                     degauss = 0.02 ,
                    smearing = 'mp' ,
 /
 &ELECTRONS
 /
 &IONS
 /
 &CELL
               cell_dynamics = 'bfgs' ,
 /
ATOMIC_SPECIES
   Al  26.98  Al.pbe-nl-rrkjus_psl.1.0.0.UPF
ATOMIC_POSITIONS alat
   Al    0.000000000    0.000000000    0.000000000
K_POINTS automatic
  20 20 20  0 0 0

[Al.vc-relax.out]

Begin final coordinates
     new unit-cell volume =    111.15446 a.u.^3 (    16.47139 Ang^3 )
     density =      2.71995 g/cm^3

CELL_PARAMETERS (alat=  7.68970000)
  -0.496275584  -0.000000000   0.496275584
   0.000000000   0.496275584   0.496275584
  -0.496275584   0.496275584   0.000000000

ATOMIC_POSITIONS (alat)
Al            0.0000000000        0.0000000000        0.0000000000
End final coordinates

[Al.eos]

# equation of state: birch 1st order.  chisq =   0.5139D-05
# a0 =  7.6897 a.u., k0 =  678 kbar, dk0 =  4.27 d2k0 =  0.000 emin =   -5.03767
# a0 =  4.06919 Ang, k0 =  67.8 GPa,  V0 =   113.67 (a.u.)^3,  V0 =   16.84 A^3 

#########################################################################
# Lat.Par       E_calc        E_fit       E_diff    Pressure      Enthalpy
# a.u.            Ry           Ry            Ry        GPa           Ry
#########################################################################
  5.60000      -4.52379      -4.52017    -0.00362     518.54       -2.97618
  5.80000      -4.66251      -4.66460     0.00208     364.14       -3.45508
  6.00000      -4.76977      -4.77322     0.00346     255.35       -3.83242
  6.20000      -4.85181      -4.85448     0.00267     178.18       -4.13015
  6.40000      -4.91365      -4.91472     0.00107     123.13       -4.36511
  6.60000      -4.95932      -4.95872    -0.00060      83.70       -4.55036
  6.80000      -4.99207      -4.99014    -0.00193      55.39       -4.69607
  7.00000      -5.01447      -5.01177    -0.00270      35.05       -4.81018
  7.20000      -5.02866      -5.02579    -0.00287      20.44       -4.89899
  7.40000      -5.03643      -5.03388    -0.00255      10.00       -4.96759
  7.60000      -5.03924      -5.03734    -0.00191       2.57       -5.02006
  7.80000      -5.03820      -5.03721    -0.00100      -2.65       -5.05954
  8.00000      -5.03420      -5.03429     0.00009      -6.25       -5.08860
  8.20000      -5.02805      -5.02924     0.00119      -8.68       -5.10937
  8.40000      -5.02050      -5.02254     0.00205     -10.24       -5.12368
  8.60000      -5.01207      -5.01462     0.00254     -11.18       -5.13294
  8.80000      -5.00306      -5.00577     0.00271     -11.66       -5.13815
  9.00000      -4.99371      -4.99627     0.00256     -11.82       -5.14014
  9.20000      -4.98419      -4.98631     0.00212     -11.74       -5.13957
  9.40000      -4.97465      -4.97605     0.00140     -11.50       -5.13698
  9.60000      -4.96521      -4.96562     0.00042     -11.15       -5.13281
  9.80000      -4.95596      -4.95513    -0.00083     -10.72       -5.12745
 10.00000      -4.94697      -4.94465    -0.00232     -10.25       -5.12118
 10.20000      -4.93828      -4.93424    -0.00403      -9.76       -5.11423