<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">not “unphysical” just inaccurate … SB<div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 5 Apr 2018, at 19:39, Jie Peng <<a href="mailto:jiepeng@umd.edu" class="">jiepeng@umd.edu</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class="">Stefano:<div class=""><br class=""></div><div class="">I think that is right on the spot! Let me do a calculation using Gamma point only in pwscf and then compare again.</div><div class=""><br class=""></div><div class="">So for cp.x, in order to get an accurate lattice structure, one would have to use a n*n*n supercell instead of a unit cell since it can only process real wavefunctions that are located at Gamma point only. Computations done on a single unit cell using cp.x code, therefore usually produces results that are unphysical. Is this the correct way to interpretate?</div><div class=""><br class=""></div><div class="">Thank you very much!</div><div class=""><br class=""></div><div class="">Best</div><div class="">Jie</div></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Thu, Apr 5, 2018 at 2:22 AM, Stefano de Gironcoli <span dir="ltr" class=""><<a href="mailto:degironc@sissa.it" target="_blank" class="">degironc@sissa.it</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
  
    
  
  <div bgcolor="#FFFFFF" text="#000000" class=""><p class=""><tt class="">Dear </tt>Jie Peng,</p><p class="">   the cp.x code assumes gamma point sampling and does not
      process your k-point definition card, while pw.x is using, a
      rather dense, grid of points in the BZ.</p><p class="">  I think this is the most relevant difference in your two
      inputs.</p><p class="">  To see if this is the case you can repeat the pw.x calculation
      with <br class="">
    </p><p class="">K_POINT Gamma<br class="">
    </p><p class="">  Is the 10 8 8 grid really necessary ? is the system metallic ?
      <br class="">
    </p><p class="">  if not I guess a smaller grid (like  6 4 4 or less) could be
      sufficient and then you could use the cp.x code with a
      corresponding supercell  if you wish so.<br class="">
    </p><p class="">stefano<br class="">
    </p><div class=""><div class="h5">
    <br class="">
    <div class="m_4773530265834723698moz-cite-prefix">On 05/04/2018 04:16, Jie Peng wrote:<br class="">
    </div>
    </div></div><blockquote type="cite" class=""><div class=""><div class="h5">
      <div dir="ltr" class="">Dear all Quantum Espresso users:
        <div class=""><br class="">
        </div>
        <div class="">I have used pw.x and cp.x code to compute equilibrium
          lattice structure of 1T-HfS2 (Halfnium Disulfide)
          respectively, and I find that they give very different
          results.</div>
        <div class=""><br class="">
        </div>
        <div class=""><b class="">For pwscf simulation, the input file are given below.</b></div>
        <div class="">
          <div class=""><i class="">&control</i></div>
          <div class=""><i class="">    calculation='vc-relax',</i></div>
          <div class=""><i class="">!    restart_mode='from_scratch',</i></div>
          <div class=""><i class="">    tstress = .true.</i></div>
          <div class=""><i class="">    tprnfor = .true.</i></div>
          <div class=""><i class="">   </i></div>
          <div class=""><i class="">    wf_collect=.true.</i></div>
          <div class=""><i class="">    etot_conv_thr=1e-6</i></div>
          <div class=""><i class="">    forc_conv_thr=1e-5</i></div>
          <div class=""><i class="">    prefix='Hf',</i></div>
          <div class=""><i class="">    pseudo_dir='/potential'</i></div>
          <div class=""><i class="">    outdir='./tmp/',</i></div>
          <div class=""><i class=""> /</i></div>
          <div class=""><i class=""> &system</i></div>
          <div class=""><i class="">    ibrav= 4,</i></div>
          <div class=""><i class="">    a=3.6529</i></div>
          <div class=""><i class="">   c=5.6544</i></div>
          <div class=""><i class="">    nat=  3, ntyp= 2,</i></div>
          <div class=""><i class="">    ecutwfc =50</i></div>
          <div class=""><i class="">    vdw_corr='DFT-D',</i></div>
          <div class=""><i class=""> !   lspinorb=.true.</i></div>
          <div class=""><i class=""> !   noncolin=.true.</i></div>
          <div class=""><i class=""> !   ecutrho=300</i></div>
          <div class=""><i class=""> !   nbnd=14</i></div>
          <div class=""><i class="">!    occupations='smearing'</i></div>
          <div class=""><i class="">!    smearing='gaussian'</i></div>
          <div class=""><i class="">!   degauss=0.01</i></div>
          <div class=""><i class=""> !  nspin=2</i></div>
          <div class=""><i class=""> !   starting_magnetization(1)=0.1</i></div>
          <div class=""><i class="">/</i></div>
          <div class=""><i class=""> &electrons</i></div>
          <div class=""><i class="">    conv_thr=1e-12</i></div>
          <div class=""><i class="">    mixing_beta = 0.7</i></div>
          <div class=""><i class="">/</i></div>
          <div class=""><i class=""> &ions</i></div>
          <div class=""><i class="">    ion_dynamics = 'bfgs'</i></div>
          <div class=""><i class=""> /</i></div>
          <div class=""><i class=""> &cell</i></div>
          <div class=""><i class="">    cell_dynamics = 'bfgs'</i></div>
          <div class=""><i class=""> </i></div>
          <div class=""><i class="">/</i></div>
          <div class=""><i class="">ATOMIC_SPECIES</i></div>
          <div class=""><i class=""> Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
          <div class=""><i class=""> S  32.065  S.pbe-mt_fhi.UPF</i></div>
          <div class=""><i class="">ATOMIC_POSITIONS (crystal)</i></div>
          <div class=""><i class="">Hf      -0.000000000  -0.000000000  -0.000000000</i></div>
          <div class=""><i class="">S        0.666666667   0.333333333   0.257234636</i></div>
          <div class=""><i class="">S        0.333333333   0.666666667  -0.257234636</i></div>
          <div class=""><i class=""> K_POINTS automatic</i></div>
          <div class=""><i class="">10 8 8 0 0 0</i></div>
          <div class=""><br class="">
          </div>
          <div class="">The relaxed lattice structure is the one included in this
            input file (I first did the full relaxation after which I
            copied the resulting relaxed lattice structure into this
            input file, then modified this file to compute electronic
            structure and phonons). The forces acting on atoms are small
            and I believe this should be the equilibrium structure of
            1T-HfS2.</div>
          <div class=""><br class="">
          </div>
          <div class="">
            <div class=""><i class="">     Forces acting on atoms (Ry/au):</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">     atom    1 type  1   force =     0.00000000   
                0.00000000    0.00000000</i></div>
            <div class=""><i class="">     atom    2 type  2   force =     0.00000000   
                0.00000000   -0.00001404</i></div>
            <div class=""><i class="">     atom    3 type  2   force =    -0.00000000   
                0.00000000    0.00001404</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">     Total force =     0.000020     Total SCF
                correction =     0.000001</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">     entering subroutine stress ...</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">          total   stress  (Ry/bohr**3)             
                     (kbar)     P=   -0.16</i></div>
            <div class=""><i class="">  -0.00000129  -0.00000000   0.00000000       
                 -0.19     -0.00      0.00</i></div>
            <div class=""><i class="">  -0.00000000  -0.00000129   0.00000000       
                 -0.00     -0.19      0.00</i></div>
            <div class=""><i class="">   0.00000000   0.00000000  -0.00000078         
                0.00      0.00     -0.12</i></div>
          </div>
          <div class=""><i class=""><br class="">
            </i></div>
          <div class=""><b class="">For cp.x, </b>I carefully follow the steps required
            to carry out a CP simulations: Relax electronic structure to
            ground state -> Relax the ion positions -> relax the
            cells. The input files are attached below.</div>
          <div class=""><br class="">
          </div>
          <div class=""><b class="">Electronic relaxation</b></div>
          <div class="">
            <div class=""><i class="">&control</i></div>
            <div class=""><i class="">    calculation='cp',</i></div>
            <div class=""><i class="">    title='Halfnium disulfide'</i></div>
            <div class=""><i class="">    restart_mode='from_scratch',</i></div>
            <div class=""><i class="">    ndr=50,</i></div>
            <div class=""><i class="">    ndw=50,</i></div>
            <div class=""><i class="">    nstep=10000,</i></div>
            <div class=""><i class="">    iprint=100</i></div>
            <div class=""><i class="">    isave=100,</i></div>
            <div class=""><i class="">    tstress = .true.</i></div>
            <div class=""><i class="">    tprnfor = .true.</i></div>
            <div class=""><i class="">    dt=10,</i></div>
            <div class=""><i class="">    wf_collect=.true.</i></div>
            <div class=""><i class="">    etot_conv_thr=1e-6</i></div>
            <div class=""><i class="">    forc_conv_thr=1e-3</i></div>
            <div class=""><i class="">    ekin_conv_thr=1e-5</i></div>
            <div class=""><i class="">    prefix='HfS2',</i></div>
            <div class=""><i class="">    pseudo_dir='/home/jpeng/HfS2/<wbr class="">potential'</i></div>
            <div class=""><i class="">    outdir='./tmp/',</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &system</i></div>
            <div class=""><i class="">    ibrav= 4,</i></div>
            <div class=""><i class="">    a=3.6529</i></div>
            <div class=""><i class="">   c=5.6544</i></div>
            <div class=""><i class="">    nat=  3, ntyp= 2,</i></div>
            <div class=""><i class="">    ecutwfc =50</i></div>
            <div class=""><i class="">    vdw_corr='DFT-D',</i></div>
            <div class=""><i class=""> !   lspinorb=.true.</i></div>
            <div class=""><i class=""> !   noncolin=.true.</i></div>
            <div class=""><i class=""> !   ecutrho=300</i></div>
            <div class=""><i class=""> !   nbnd=14</i></div>
            <div class=""><i class="">!    occupations='smearing'</i></div>
            <div class=""><i class="">!    smearing='gaussian'</i></div>
            <div class=""><i class="">!   degauss=0.01</i></div>
            <div class=""><i class=""> !  nspin=2</i></div>
            <div class=""><i class=""> !   starting_magnetization(1)=0.1</i></div>
            <div class=""><i class="">! Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">! S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &electrons</i></div>
            <div class=""><i class="">    electron_dynamics='damp'</i></div>
            <div class=""><i class="">!    electron_velocities='zero'</i></div>
            <div class=""><i class="">    emass=400</i></div>
            <div class=""><i class="">    emass_cutoff=1</i></div>
            <div class=""><i class="">    electron_damping=0.1</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &ions</i></div>
            <div class=""><i class="">    ion_dynamics = 'none'</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &cell</i></div>
            <div class=""><i class="">    cell_dynamics = 'none'</i></div>
            <div class=""><i class=""> </i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class="">ATOMIC_SPECIES</i></div>
            <div class=""><i class=""> Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class=""> S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">ATOMIC_POSITIONS (crystal)</i></div>
            <div class=""><i class="">Hf      -0.000000000  -0.000000000  -0.000000000</i></div>
            <div class=""><i class="">S        0.666666667   0.333333333   0.257234636</i></div>
            <div class=""><i class="">S        0.333333333   0.666666667  -0.257234636</i></div>
            <div class=""><i class=""> K_POINTS automatic</i></div>
            <div class=""><i class="">10 8 8 0 0 0</i></div>
            <div style="font-weight:bold" class=""><br class="">
            </div>
          </div>
          <div style="font-weight:bold" class="">Ion relaxation</div>
          <div class="">
            <div class=""><i class="">&control</i></div>
            <div class=""><i class="">    calculation='cp',</i></div>
            <div class=""><i class="">    title='Halfnium disulfide'</i></div>
            <div class=""><i class="">    restart_mode='restart',</i></div>
            <div class=""><i class="">    ndr=50,</i></div>
            <div class=""><i class="">    ndw=51,</i></div>
            <div class=""><i class="">    nstep=50000,</i></div>
            <div class=""><i class="">    iprint=100</i></div>
            <div class=""><i class="">    isave=100,</i></div>
            <div class=""><i class="">    tstress = .true.</i></div>
            <div class=""><i class="">    tprnfor = .true.</i></div>
            <div class=""><i class="">    dt=10,</i></div>
            <div class=""><i class="">    wf_collect=.true.</i></div>
            <div class=""><i class="">    etot_conv_thr=1e-6</i></div>
            <div class=""><i class="">    forc_conv_thr=1e-3</i></div>
            <div class=""><i class="">    ekin_conv_thr=1e-5</i></div>
            <div class=""><i class="">    prefix='HfS2',</i></div>
            <div class=""><i class="">    pseudo_dir='/home/jpeng/HfS2/<wbr class="">potential'</i></div>
            <div class=""><i class="">    outdir='./tmp/',</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &system</i></div>
            <div class=""><i class="">    ibrav= 4,</i></div>
            <div class=""><i class="">    a=3.6529</i></div>
            <div class=""><i class="">   c=5.6544</i></div>
            <div class=""><i class="">    nat=  3, ntyp= 2,</i></div>
            <div class=""><i class="">    ecutwfc =50</i></div>
            <div class=""><i class="">    vdw_corr='DFT-D',</i></div>
            <div class=""><i class=""> !   lspinorb=.true.</i></div>
            <div class=""><i class=""> !   noncolin=.true.</i></div>
            <div class=""><i class=""> !   ecutrho=300</i></div>
            <div class=""><i class=""> !   nbnd=14</i></div>
            <div class=""><i class="">!    occupations='smearing'</i></div>
            <div class=""><i class="">!    smearing='gaussian'</i></div>
            <div class=""><i class="">!   degauss=0.01</i></div>
            <div class=""><i class=""> !  nspin=2</i></div>
            <div class=""><i class=""> !   starting_magnetization(1)=0.1</i></div>
            <div class=""><i class="">! Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">! S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &electrons</i></div>
            <div class=""><i class="">    electron_dynamics='damp'</i></div>
            <div class=""><i class="">!    electron_velocities='zero'</i></div>
            <div class=""><i class="">    emass=400</i></div>
            <div class=""><i class="">    emass_cutoff=1</i></div>
            <div class=""><i class="">    electron_damping=0.1</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &ions</i></div>
            <div class=""><i class="">    ion_dynamics = 'damp'</i></div>
            <div class=""><i class="">    ion_damping=0.1</i></div>
            <div class=""><i class="">    ion_nstepe=10</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &cell</i></div>
            <div class=""><i class="">    cell_dynamics = 'none'</i></div>
            <div class=""><i class=""> </i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class="">ATOMIC_SPECIES</i></div>
            <div class=""><i class=""> Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class=""> S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">ATOMIC_POSITIONS (crystal)</i></div>
            <div class=""><i class="">Hf      -0.000000000  -0.000000000  -0.000000000</i></div>
            <div class=""><i class="">S        0.666666667   0.333333333   0.257234636</i></div>
            <div class=""><i class="">S        0.333333333   0.666666667  -0.257234636</i></div>
            <div class=""><i class=""> K_POINTS automatic</i></div>
            <div class=""><i class="">10 8 8 0 0 0</i></div>
            <div style="font-weight:bold" class=""><br class="">
            </div>
          </div>
          <div style="font-weight:bold" class="">Cell relaxation</div>
          <div class="">
            <div class=""><i class="">&control</i></div>
            <div class=""><i class="">    calculation='vc-cp',</i></div>
            <div class=""><i class="">    title='Halfnium disulfide'</i></div>
            <div class=""><i class="">    restart_mode='reset_counters',</i></div>
            <div class=""><i class="">    ndr=51,</i></div>
            <div class=""><i class="">    ndw=52,</i></div>
            <div class=""><i class="">    nstep=50000,</i></div>
            <div class=""><i class="">    iprint=100</i></div>
            <div class=""><i class="">    isave=100,</i></div>
            <div class=""><i class="">    tstress = .true.</i></div>
            <div class=""><i class="">    tprnfor = .true.</i></div>
            <div class=""><i class="">    dt=10,</i></div>
            <div class=""><i class="">    wf_collect=.true.</i></div>
            <div class=""><i class="">    etot_conv_thr=1e-6</i></div>
            <div class=""><i class="">    forc_conv_thr=1e-3</i></div>
            <div class=""><i class="">    ekin_conv_thr=1e-5</i></div>
            <div class=""><i class="">    prefix='HfS2',</i></div>
            <div class=""><i class="">    pseudo_dir='/home/jpeng/HfS2/<wbr class="">potential'</i></div>
            <div class=""><i class="">    outdir='./tmp/',</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &system</i></div>
            <div class=""><i class="">    ibrav= 4,</i></div>
            <div class=""><i class="">    a=3.6529</i></div>
            <div class=""><i class="">   c=5.6544</i></div>
            <div class=""><i class="">    nat=  3, ntyp= 2,</i></div>
            <div class=""><i class="">    ecutwfc =50</i></div>
            <div class=""><i class="">    vdw_corr='DFT-D',</i></div>
            <div class=""><i class=""> !   lspinorb=.true.</i></div>
            <div class=""><i class=""> !   noncolin=.true.</i></div>
            <div class=""><i class=""> !   ecutrho=300</i></div>
            <div class=""><i class=""> !   nbnd=14</i></div>
            <div class=""><i class="">!    occupations='smearing'</i></div>
            <div class=""><i class="">!    smearing='gaussian'</i></div>
            <div class=""><i class="">!   degauss=0.01</i></div>
            <div class=""><i class=""> !  nspin=2</i></div>
            <div class=""><i class=""> !   starting_magnetization(1)=0.1</i></div>
            <div class=""><i class="">! Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">! S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &electrons</i></div>
            <div class=""><i class="">    electron_dynamics='damp'</i></div>
            <div class=""><i class="">!    electron_velocities='zero'</i></div>
            <div class=""><i class="">    emass=400</i></div>
            <div class=""><i class="">    emass_cutoff=1</i></div>
            <div class=""><i class="">    electron_damping=0.1</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class=""> &ions</i></div>
            <div class=""><i class="">    ion_dynamics = 'damp'</i></div>
            <div class=""><i class="">    ion_damping=0.1</i></div>
            <div class=""><i class="">    ion_nstepe=10</i></div>
            <div class=""><i class=""> /</i></div>
            <div class=""><i class=""> &cell</i></div>
            <div class=""><i class="">    cell_dynamics = 'pr'</i></div>
            <div class=""><i class="">!    cell_damping=0.1</i></div>
            <div class=""><i class="">!    cell_dofree=volume</i></div>
            <div class=""><i class="">/</i></div>
            <div class=""><i class="">ATOMIC_SPECIES</i></div>
            <div class=""><i class=""> Hf  95.94  Hf.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class=""> S  32.065  S.pbe-mt_fhi.UPF</i></div>
            <div class=""><i class="">ATOMIC_POSITIONS (crystal)</i></div>
            <div class=""><i class="">Hf      -0.000000000  -0.000000000  -0.000000000</i></div>
            <div class=""><i class="">S        0.666666667   0.333333333   0.257234636</i></div>
            <div class=""><i class="">S        0.333333333   0.666666667  -0.257234636</i></div>
            <div class=""><i class=""> K_POINTS automatic</i></div>
            <div class=""><i class="">10 8 8 0 0 0</i></div>
            <div style="font-weight:bold" class=""><br class="">
            </div>
          </div>
          <div style="font-weight:bold" class="">The final equilibrium lattice
            structure obtained by cp.x is:</div>
          <div class="">
            <div class=""><b class=""> </b><i class="">  CELL_PARAMETERS</i></div>
            <div class=""><i class="">    8.27944202   -3.49986616   -1.28541441</i></div>
            <div class=""><i class="">    0.43381045    6.25063702   -0.26433640</i></div>
            <div class=""><i class="">   -1.81611680   -0.30736678    9.28229385</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   System Density [g/cm^3] :             
                3.7550323993</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   System Volume [A.U.^3] :           
                477.6950599279</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Center of mass square displacement (a.u.): 
                 0.271737</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Total stress (GPa)</i></div>
            <div class=""><i class="">       -0.00003957         0.00000336       
                 0.00017132</i></div>
            <div class=""><i class="">        0.00000336        -0.00001393       
                 0.00003875</i></div>
            <div class=""><i class="">        0.00017132         0.00003875       
                 0.00048005</i></div>
            <div class=""><i class="">   ATOMIC_POSITIONS</i></div>
            <div class=""><i class="">   Hf     -0.57392945538368E+00   
                -0.32523714658422E+00    -0.78842946683202E-01</i></div>
            <div class=""><i class="">   S       0.61817237992192E+01   
                 0.34715217744206E+01     0.20852180260292E+00</i></div>
            <div class=""><i class="">   S       0.31507619982481E+00   
                 0.41860506478142E+01    -0.20961035507250E+01</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   ATOMIC_VELOCITIES</i></div>
            <div class=""><i class="">   Hf     -0.49417894612947E-07   
                -0.41246570825668E-07    -0.28182774835127E-06</i></div>
            <div class=""><i class="">   S       0.29443574450584E-06   
                 0.17988901894696E-06     0.34817154465079E-06</i></div>
            <div class=""><i class="">   S      -0.14657506118618E-06   
                -0.56477323752712E-07     0.49507043808484E-06</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Forces acting on atoms (au):</i></div>
            <div class=""><i class="">   Hf     -0.18727766763523E-03   
                -0.15291863668542E-03    -0.99976280595181E-03</i></div>
            <div class=""><i class="">   S       0.33856074345196E-03   
                 0.20689440901408E-03     0.40153992932368E-03</i></div>
            <div class=""><i class="">   S      -0.17602213243772E-03   
                -0.68887225779463E-04     0.57298561574671E-03</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class="">A visualization is attached here </div>
            <div style="font-weight:bold" class="">
              <span id="cid:part1.C12A770C.5B57FD7A@sissa.it"><image.png></span>
              <br class="">
              <br class="">
            </div>
          </div>
          <div style="font-weight:bold" class="">while by pwscf, the equilibrium
            lattice structure is:</div>
          <div class="">
            <div class=""><i class="">   CELL_PARAMETERS</i></div>
            <div class=""><i class="">    6.90298059   -3.45149030    0.00000000</i></div>
            <div class=""><i class="">    0.00000000    5.97815655    0.00000000</i></div>
            <div class=""><i class="">    0.00000000    0.00000000   10.68526745</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   System Density [g/cm^3] :             
                4.0679453101</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   System Volume [A.U.^3] :           
                440.9499858676</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Center of mass square displacement (a.u.): 
                 0.000000</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Total stress (GPa)</i></div>
            <div class=""><i class="">       32.06481501        -0.01335027       
                -0.00956254</i></div>
            <div class=""><i class="">       -0.01335027        32.07951164       
                -0.00592770</i></div>
            <div class=""><i class="">       -0.00956139        -0.00592704       
                 2.04176052</i></div>
            <div class=""><i class="">   ATOMIC_POSITIONS</i></div>
            <div class=""><i class="">   Hf      0.00000000000000E+00   
                -0.00000000000000E+00    -0.00000000000000E+00</i></div>
            <div class=""><i class="">   S       0.34514902988605E+01   
                 0.19927188491672E+01     0.27486208819801E+01</i></div>
            <div class=""><i class="">   S      -0.34514902047533E-08   
                 0.39854377043125E+01    -0.27486208819801E+01</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   ATOMIC_VELOCITIES</i></div>
            <div class=""><i class="">   Hf      0.00000000000000E+00   
                 0.00000000000000E+00     0.00000000000000E+00</i></div>
            <div class=""><i class="">   S       0.00000000000000E+00   
                 0.00000000000000E+00     0.00000000000000E+00</i></div>
            <div class=""><i class="">   S       0.00000000000000E+00   
                 0.00000000000000E+00     0.00000000000000E+00</i></div>
            <div class=""><i class=""><br class="">
              </i></div>
            <div class=""><i class="">   Forces acting on atoms (au):</i></div>
            <div class=""><i class="">   Hf      0.70847502228925E-03   
                 0.43071957102166E-03    -0.17703368862259E-04</i></div>
            <div class=""><i class="">   S      -0.52668423530029E-03   
                -0.28607208606422E-03    -0.81547327015321E-01</i></div>
            <div class=""><i class="">   S      -0.41998284595312E-03   
                -0.22039679837681E-03     0.81837284893753E-01</i></div>
            <div style="font-weight:bold" class=""><br class="">
            </div>
          </div>
          <div class="">A visulization is attached below</div>
          <div class="">
            <span id="cid:part2.BDAE1642.F544B821@sissa.it"><image.png></span>
            <br class="">
          </div>
          <div style="font-weight:bold" class=""><br class="">
          </div>
          <div style="font-weight:bold" class=""><br class="">
          </div>
          <div class="">I am expecting some difference because pw.x uses
            DFT and BFGS algorithm to relax the lattice structure while
            cp.x uses CP method, but not so large a difference.
            Especially since the lattice structure given by pw.x agrees
            with experiments and other published works, I am suspecting
            is it because I have not correctly carried out variable cell
            CP simulations. </div>
          <div class=""><br class="">
          </div>
          <div class="">Can anyone help me understand the discrepancy I
            see in the results produced by pw.x and cp.x code? Or
            pointing out any mistake I have made during my simulations?</div>
          <div class=""><br class="">
          </div>
          <div class="">Thank you in advance for your help, sincerely!<br class="">
            <br class="">
          </div>
          <div class="">Best</div>
          <div class="">Jie</div>
          -- <br class="">
          <div class="m_4773530265834723698gmail_signature">
            <div dir="ltr" class="">
              <div class="">
                <div style="font-size:12.8px" class="">------------------------------<wbr class="">------------------------------<wbr class="">------------------------------<wbr class="">------------------------------<br class="">
                  Jie Peng</div>
                <div style="font-size:12.8px" class="">PhD student<br class="">
                  2134 Glenn Martin Hall, Mechanical Engineering,
                  University of Maryland<br class="">
                  College Park, Maryland, USA<br class="">
                  Phone:(+1) 240-495-9445<br class="">
                </div>
                <div style="font-size:12.8px" class="">Email: <a href="mailto:jiepeng@umd.edu" target="_blank" class="">jiepeng@umd.edu</a><br class="">
                </div>
              </div>
              <div class=""><br class="">
              </div>
            </div>
          </div>
        </div>
      </div>
      <br class="">
      <fieldset class="m_4773530265834723698mimeAttachmentHeader"></fieldset>
      <br class="">
      </div></div><pre class="">______________________________<wbr class="">_________________
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    </blockquote>
    <br class="">
  </div>

<br class="">______________________________<wbr class="">_________________<br class="">
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