<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; color: rgb(0, 0, 0); "><div><div style="font-family: Helvetica; font-size: medium; ">Dear QE users,</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">I'm having a difficulty on a geometry optimization using 'vc-relax'.</div><div style="font-family: Helvetica; font-size: medium; ">I searched forum threads and followed various suggestions but the 'Total force' still does not converge..</div><div style="font-family: Helvetica; font-size: medium; ">(but the pressures seems to be converged)</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">The job steps I've taken as follows,</div><div style="font-family: Helvetica; font-size: medium; "><span class="Apple-style-span" style="font-size: 14px; font-family: Helvetica, sans-serif; "><br></span></div><div style="font-family: Helvetica; font-size: medium; "><span class="Apple-style-span" style="font-size: 14px; font-family: Helvetica, sans-serif; ">1. optimized k-point and ecutwfc.</span></div><div style="font-family: Helvetica; font-size: medium; ">2. optimized lattice parameter using Murnaghan fitting.</div><div style="font-family: Helvetica; font-size: medium; ">3. 'relax' the geometry using the lattice constant obtained from step2,</div><div><font class="Apple-style-span" face="Helvetica,sans-serif"><div style="font-family: Helvetica; font-size: medium; "><br></div></font><div style="font-family: Helvetica; font-size: medium; ">----------------------------------------------</div><div style="font-family: Helvetica; font-size: medium; "></div><font class="Apple-style-span" face="Helvetica,sans-serif"><div style="font-family: Helvetica; font-size: medium; ">&control</div><div style="font-family: Helvetica; font-size: medium; "> calculation = 'relax',</div><div style="font-family: Helvetica; font-size: medium; "> restart_mode = 'from_scratch',</div><div style="font-family: Helvetica; font-size: medium; "> prefix = '$NAME',</div><div style="font-family: Helvetica; font-size: medium; "> pseudo_dir = '$PSEUDO_DIR/',</div><div style="font-family: Helvetica; font-size: medium; "> outdir = '$OUT_DIR/',</div><div style="font-family: Helvetica; font-size: medium; "> wf_collect = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> tstress = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> tprnfor = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> etot_conv_thr = 1.d-7</div><div style="font-family: Helvetica; font-size: medium; "> forc_conv_thr = 1.d-6</div><div style="font-family: Helvetica; font-size: medium; "> nstep = 1000</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&system</div><div style="font-family: Helvetica; font-size: medium; "> ibrav = 0,</div><div style="font-family: Helvetica; font-size: medium; "> celldm(1) = 10.3345 </div><div style="font-family: Helvetica; font-size: medium; "> nat = 18,</div><div style="font-family: Helvetica; font-size: medium; "> ntyp = 2,</div><div style="font-family: Helvetica; font-size: medium; "> ecutwfc = 80.0,</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&electrons</div><div style="font-family: Helvetica; font-size: medium; "> diagonalization = 'cg',</div><div style="font-family: Helvetica; font-size: medium; "> mixing_mode = 'plain',</div><div style="font-family: Helvetica; font-size: medium; "> mixing_beta = 0.7,</div><div style="font-family: Helvetica; font-size: medium; "> conv_thr = 1.0d-10,</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&ions</div><div style="font-family: Helvetica; font-size: medium; "> ion_dynamics = 'bfgs'</div><div style="font-family: Helvetica; font-size: medium; "> bfgs_ndim = 3</div><div style="font-family: Helvetica; font-size: medium; "><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">ATOMIC_SPECIES</div><div style="font-family: Helvetica; font-size: medium; ">Si 28.086 Si.pbe-rrkj.UPF</div><div style="font-family: Helvetica; font-size: medium; ">H 1.0079 H.pbe-vbc.UPF</div><div style="font-family: Helvetica; font-size: medium; ">CELL_PARAMETERS</div><div style="font-family: Helvetica; font-size: medium; "> 4.89897948556636 0.00000000000000 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; "> 0.00000000000000 5.19615242270663 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; "> 0.00000000000000 0.00000000000000 0.70710678118655</div><div style="font-family: Helvetica; font-size: medium; ">ATOMIC_POSITIONS angstrom</div><div style="font-family: Helvetica; font-size: medium; ">Si 6.65158939652772 10.19066526389879 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">Si 7.76018762928234 9.40676793590657 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">Si 9.97738409479158 10.19066526389879 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">Si 11.08598232754620 9.40676793590657 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">Si 13.30317879305544 10.19066526389879 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">Si 14.41177702581006 9.40676793590657 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">Si 16.62897349131930 10.19066526389879 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">Si 17.73757172407392 9.40676793590657 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 6.65158939652772 11.67767298594874 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 7.76018762928234 7.91976021385662 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">H 9.97738409479158 11.67767298594874 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">H 11.08598232754620 7.91976021385662 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 13.30317879305544 11.67767298594874 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 14.41177702581006 7.91976021385662 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">H 16.62897349131930 11.67767298594874 1.92014846431207</div><div style="font-family: Helvetica; font-size: medium; ">H 17.73757172407392 7.91976021385662 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 5.24962507127668 9.69499602321547 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">H 19.13953604932496 9.90243717658989 0.00000000000000</div><div style="font-family: Helvetica; font-size: medium; ">K_POINTS automatic</div><div style="font-family: Helvetica; font-size: medium; ">1 1 16 0 0 0 </div><div>----------------------------------------------</div></div></font><div style="font-family: Helvetica; font-size: medium; "></div><font class="Apple-style-span" face="Helvetica,sans-serif"><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">4. check if 'Total force' is converged -> OK.</div><div style="font-family: Helvetica; font-size: medium; ">5. Take the final atomic coordinates from step4.</div><div style="font-family: Helvetica; font-size: medium; ">6. Run 'vc-relax' as,</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">----------------------------------------------</div><div style="font-family: Helvetica; font-size: medium; "><div style="font-family: Helvetica; font-size: medium; ">&control</div><div style="font-family: Helvetica; font-size: medium; "> calculation = 'vc-relax',</div><div style="font-family: Helvetica; font-size: medium; "> restart_mode = 'from_scratch',</div><div style="font-family: Helvetica; font-size: medium; "> prefix = '$NAME',</div><div style="font-family: Helvetica; font-size: medium; "> pseudo_dir = '$PSEUDO_DIR/',</div><div style="font-family: Helvetica; font-size: medium; "> outdir = '$OUT_DIR/',</div><div style="font-family: Helvetica; font-size: medium; "> wf_collect = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> tstress = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> tprnfor = .TRUE.</div><div style="font-family: Helvetica; font-size: medium; "> etot_conv_thr = 1.d-6</div><div style="font-family: Helvetica; font-size: medium; "> forc_conv_thr = 1.d-6</div><div style="font-family: Helvetica; font-size: medium; "> nstep = 10000</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&system</div><div style="font-family: Helvetica; font-size: medium; "> ibrav = 0,</div><div style="font-family: Helvetica; font-size: medium; "> celldm(1) = 10.3345 </div><div style="font-family: Helvetica; font-size: medium; "> nat = 18,</div><div style="font-family: Helvetica; font-size: medium; "> ntyp = 2,</div><div style="font-family: Helvetica; font-size: medium; "> ecutwfc = 80.0,</div><div style="font-family: Helvetica; font-size: medium; "> ecfixed = 70.0,</div><div style="font-family: Helvetica; font-size: medium; "> qcutz = 150.0,</div><div style="font-family: Helvetica; font-size: medium; "> q2sigma = 4.0,</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&electrons</div><div style="font-family: Helvetica; font-size: medium; "> diagonalization = 'cg',</div><div style="font-family: Helvetica; font-size: medium; "> mixing_mode = 'plain',</div><div style="font-family: Helvetica; font-size: medium; "> mixing_beta = 0.7,</div><div style="font-family: Helvetica; font-size: medium; "> conv_thr = 1.0d-10,</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&ions</div><div style="font-family: Helvetica; font-size: medium; "> ion_dynamics = 'bfgs'</div><div style="font-family: Helvetica; font-size: medium; "> bfgs_ndim = 3</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">&cell</div><div style="font-family: Helvetica; font-size: medium; "> cell_dynamics = 'bfgs'</div><div style="font-family: Helvetica; font-size: medium; "> press_conv_thr = 0.1d0</div><div style="font-family: Helvetica; font-size: medium; "> press = 0.d0</div><div style="font-family: Helvetica; font-size: medium; "> cell_factor = 2.d0</div><div style="font-family: Helvetica; font-size: medium; ">/</div><div style="font-family: Helvetica; font-size: medium; ">ATOMIC_SPECIES</div><div style="font-family: Helvetica; font-size: medium; ">Si 28.086 Si.pbe-rrkj.UPF</div><div style="font-family: Helvetica; font-size: medium; ">H 1.0079 H.pbe-vbc.UPF</div><div><div>CELL_PARAMETERS</div><div> 4.89897948556636 0.00000000000000 0.00000000000000</div><div> 0.00000000000000 5.19615242270663 0.00000000000000</div><div> 0.00000000000000 0.00000000000000 0.70710678118655</div><div>ATOMIC_POSITIONS angstrom</div><div>Si 6.595371055 10.174313717 -0.005918138</div><div>Si 7.697686348 9.425353751 1.927575025</div><div>Si 9.940638827 10.152944754 1.927571298</div><div>Si 11.073523827 9.431959516 -0.005942277</div><div>Si 13.315586210 10.165270258 -0.005944217</div><div>Si 14.448496999 9.444343582 1.927568680</div><div>Si 16.691414457 10.172072841 1.927571881</div><div>Si 17.793848036 9.423269303 -0.005921592</div><div>H 6.597479872 11.672720999 -0.006012302</div><div>H 7.704912055 7.923796337 1.927472273</div><div>H 9.942740551 11.655007902 1.927566837</div><div>H 11.078852672 7.930134628 -0.005961188</div><div>H 13.310208995 11.667097994 -0.005963695</div><div>H 14.446478909 7.942288221 1.927563469</div><div>H 16.684085788 11.673634035 1.927468080</div><div>H 17.791980426 7.924865718 -0.006016781</div><div>H 5.166205416 9.718188689 -0.005743345</div><div>H 19.222939638 9.879636554 -0.005746296</div><div>K_POINTS automatic</div><div>1 1 16 0 0 0 </div></div></div></font><div style="font-family: Helvetica; font-size: medium; ">----------------------------------------------</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">Then the output 'Total force' seems to oscillates and does not converge as shown below,</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; "><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; ">-----------------------------------------------------------------------------------------</span></div><div style="font-family: Helvetica; font-size: medium; "><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; "> Total force = 0.000723 Total SCF correction = 0.000009</span></div><font class="Apple-style-span" face="Helvetica,sans-serif"><div><div> Total force = 0.000288 Total SCF correction = 0.000010</div><div> Total force = 0.000172 Total SCF correction = 0.000001</div><div> Total force = 0.000227 Total SCF correction = 0.000005</div><div> Total force = 0.000323 Total SCF correction = 0.000005</div><div> Total force = 0.000327 Total SCF correction = 0.000004</div><div> Total force = 0.000393 Total SCF correction = 0.000004</div><div> Total force = 0.000682 Total SCF correction = 0.000004</div><div> Total force = 0.000811 Total SCF correction = 0.000006</div><div> Total force = 0.000803 Total SCF correction = 0.000007</div><div> Total force = 0.000427 Total SCF correction = 0.000001</div><div> Total force = 0.000392 Total SCF correction = 0.000002</div><div> Total force = 0.000380 Total SCF correction = 0.000001</div><div> Total force = 0.000233 Total SCF correction = 0.000001</div><div> Total force = 0.000164 Total SCF correction = 0.000001</div><div> Total force = 0.000227 Total SCF correction = 0.000001</div><div> Total force = 0.000246 Total SCF correction = 0.000000</div><div> Total force = 0.000299 Total SCF correction = 0.000001</div><div> Total force = 0.000320 Total SCF correction = 0.000001</div><div> Total force = 0.000230 Total SCF correction = 0.000001</div><div> Total force = 0.000129 Total SCF correction = 0.000001</div><div> Total force = 0.000147 Total SCF correction = 0.000000</div><div> Total force = 0.000131 Total SCF correction = 0.000001</div><div> Total force = 0.000104 Total SCF correction = 0.000000</div><div> Total force = 0.000116 Total SCF correction = 0.000001</div><div> Total force = 0.000146 Total SCF correction = 0.000000</div><div> Total force = 0.000180 Total SCF correction = 0.000001</div><div> Total force = 0.000195 Total SCF correction = 0.000000</div><div> Total force = 0.000193 Total SCF correction = 0.000001</div><div> Total force = 0.000194 Total SCF correction = 0.000001</div><div> Total force = 0.000208 Total SCF correction = 0.000000</div><div> Total force = 0.000271 Total SCF correction = 0.000001</div><div> Total force = 0.000336 Total SCF correction = 0.000000</div><div> Total force = 0.000350 Total SCF correction = 0.000001</div><div> Total force = 0.000355 Total SCF correction = 0.000001</div><div> Total force = 0.000356 Total SCF correction = 0.000001</div><div> Total force = 0.000351 Total SCF correction = 0.000000</div><div> Total force = 0.000364 Total SCF correction = 0.000000</div><div> Total force = 0.000437 Total SCF correction = 0.000000</div><div> Total force = 0.000509 Total SCF correction = 0.000000</div><div> Total force = 0.000542 Total SCF correction = 0.000002</div><div> Total force = 0.000520 Total SCF correction = 0.000001</div></div></font><div style="font-family: Helvetica; font-size: medium; "><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; ">-----------------------------------------------------------------------------------------</span></div><div><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; "><br></span></div><div><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; "><br></span></div><div><span class="Apple-style-span" style="font-family: Helvetica, sans-serif; ">I also previously tried without </span>ecfixed, qcutz, q2sigma options but the force did not converge as well.</div><div>Any suggestions would be greatly appreciated.</div><div>Thank you.</div></div><div><br></div><div>Sincerely,</div><div style="font-family: Helvetica; font-size: medium; "><br></div><div style="font-family: Helvetica; font-size: medium; ">JISEOK KIM, Ph.D.</div><div style="font-family: Helvetica; font-size: medium; ">Postdoctoral Research Associate</div><div style="font-family: Helvetica; font-size: medium; ">Department of Materials Science and Engineering</div><div style="font-family: Helvetica; font-size: medium; ">University of Texas at Dallas</div><div style="font-family: Helvetica; font-size: medium; ">800 W. Campbell Rd. RL10</div><div style="font-family: Helvetica; font-size: medium; ">Richardson, TX 75080</div></div><div style="font-family: Helvetica, sans-serif; font-size: 14px; "><br></div></body></html>