[Pw_forum] New BFGS file updated and the results is coming up.

[vega lew]

Dear all,

Paulatto gave me the new file for BFGS calculation. I have recompiled my QE and finished the same calculation
for Anatase cell parameters. The results is my calculation can be finished without stop at errors. But the parameters
is still smaller than literature both majority DFT calculation and experimental data. The parameters are, a=3.7559 
b=3.75561 c=9.3978, respectively.
My input file as follows, 

&CONTROL
                       title = 'Anatase lattice' ,
                 calculation = 'vc-relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = '/home/vega/espresso-4.0/tmp/' ,
                      wfcdir = '/tmp/' ,
                  pseudo_dir = '/home/vega/espresso-4.0/pseudo/' ,
                      prefix = 'Anatase lattice default' ,
                     disk_io = 'none' ,
               etot_conv_thr = 0.000000735 ,
               forc_conv_thr = 0.0011668141375 ,
                       nstep = 1000 ,
 /
 &SYSTEM
                       ibrav = 6,
                   celldm(1) = 7.1469,
                   celldm(3) = 2.5124,
                         nat = 12,
                        ntyp = 2,
                     ecutwfc = 25 ,
                     ecutrho = 200 ,
 /
 &ELECTRONS
                    conv_thr = 7.3D-8 ,
 /
 &IONS
                ion_dynamics = 'bfgs' ,
 /
 &CELL
               cell_dynamics = 'bfgs' ,
 /
ATOMIC_SPECIES
   Ti   47.86700  Ti.pw91-sp-van_ak.UPF 
    O   15.99940  O.pw91-van_ak.UPF 
ATOMIC_POSITIONS angstrom 
   Ti      0.000000000    0.000000000    0.000000000    
   Ti      1.888000000    1.888000000    4.743000000    
   Ti      0.000000000    1.888000000    2.372000000    
   Ti      1.888000000    0.000000000    7.115000000    
    O      0.000000000    0.000000000    1.973000000    
    O      1.888000000    1.888000000    6.716000000    
    O      0.000000000    1.888000000    4.345000000    
    O      1.888000000    0.000000000    9.088000000    
    O      1.888000000    0.000000000    5.141000000    
    O      0.000000000    1.888000000    0.398000000    
    O      1.888000000    1.888000000    2.770000000    
    O      0.000000000    0.000000000    7.513000000    
K_POINTS automatic 
  4 4 2   1 1 1 

I think there must be something wrong with my input file. Could you please do me a 
favor tell me what's wrong and why the cell parameters so small I'm thinking about it 
day and night.

By the way, I note that CASTEP has find 32 symmetry operations of my cell. My cell is 
a standard anatase crystall. But Q-E only can find 4 at most since I adjust parameters of 
~/espresso-4.0/PW/eqvect.f90. Do this matter effect my results significantly?

I'm look forwar for your advice.

Vega Lew
PH.D Candidate in Chemical Engineering

State Key Laboratory of Materials-oriented Chemical Engineering
College of Chemistry and Chemical Engineering
Nanjing University of Technology, 210009, Nanjing, Jiangsu, China



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