[Pw_forum] question about the stress in relax process

[Wang Di]

Dear all

I perform the relax calculate to the crystal structure. After 11 step bfgs,
the total force and total scf correction had reach to the criterion,
however, the total stress was so big P=-3443.87. I have no idea about deal
with the case,  could anyone give some advices? Thanks in advance.

the input file
: &CONTROL
                 calculation = 'scf' ,
                restart_mode = 'from_scratch' ,
                  wf_collect = .true. ,
                      outdir = '/lustre/AIOFM/gxgu/workLCAF/5/temp/' ,
                      wfcdir = '/lustre/AIOFM/gxgu/workLCAF/5/wftemp/' ,
                  pseudo_dir = '/home/AIOFM/gxgu/work/NCPP/' ,
                      prefix = 'LCAF' ,
               etot_conv_thr = 1.0D-7 ,
               forc_conv_thr = 1.0D-6 ,
                       nstep = 100 ,
                     tstress = .true. ,
                     tprnfor = .true. ,
                    dipfield = .true. ,
 /
 &SYSTEM
                       ibrav = 4,
                   celldm(1) = 9.42432151,
                   celldm(3) = 1.94804220,
                         nat = 18,
                        ntyp = 4,
                     ecutwfc = 30 ,
                     ecutrho = 120 ,
                       nosym = .false. ,
 /
 &ELECTRONS
            electron_maxstep = 100,
                    conv_thr = 1.0D-10 ,
 /
ATOMIC_SPECIES
   Li    6.94100  03-Li.LDA.fhi.UPF
   Al   26.98154  13-Al.LDA.fhi.UPF
   Ca   40.07800  20-Ca.LDA.fhi.UPF
    F   18.99840  09-F.LDA.fhi.UPF
ATOMIC_POSITIONS crystal
   Li      0.333333333    0.666666667    0.250000000
   Li     -0.333333333   -0.666666667   -0.250000000
    F      0.389997       0.045970       0.148326
    F     -0.045970       0.344027       0.148326
    F     -0.344027      -0.389997       0.148326
    F     -0.045970      -0.389997       0.351674
    F     -0.344027       0.045970       0.351674
    F      0.389997       0.344027       0.351674
    F     -0.389997      -0.045970      -0.148326
    F      0.045970      -0.344027      -0.148326
    F      0.344027       0.389997      -0.148326
    F      0.045970       0.389997       0.648326
    F      0.344027      -0.045970       0.648326
    F     -0.389997      -0.344027       0.648326
   Al      0.666666667    0.333333333    0.250000000
   Al     -0.666666667   -0.333333333   -0.250000000
   Ca      0.000000000    0.000000000    0.000000000
   Ca      0.000000000    0.000000000    0.500000000
K_POINTS automatic
  16 16 16   0 0 0

best regart

Wang Di

-- 
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*Wang Di**
The Crystal Lab,*
*AnHui Institute of Optics and Fine Mechanics, ***
*Chinese Academy of Sciences,**
No350. , Shushanhu Road, Hefei, 230031, China**,
E-mail: didi5158 @gmail.ocm** ,*
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