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Dear QE users and experts,
</p>
<p style="font-family:SimSun;">
<br>
</p>
<p style="font-family:SimSun;">
I am pretty confused by the different outputed stress value from both
</p>
<p style="font-family:SimSun;">
the vc-relax (the last step) and scf steps. Could you please help me
</p>
<p style="font-family:SimSun;">
to figure out why. Thank you so much!
</p>
<p style="font-family:SimSun;">
<br>
</p>
<p style="font-family:SimSun;">
Ted
</p>
<p style="font-family:SimSun;">
<br>
</p>
<p style="font-family:SimSun;">
<br>
</p>
<p style="font-family:SimSun;">
Here is the output stress from the last step of vc-relax:
</p>
<p style="font-family:SimSun;">
total stress (Ry/bohr**3) (kbar) P= 0.01<br>
0.00000028 -0.00000000 -0.00000013 0.04 -0.00 -0.02<br>
-0.00000000 -0.00000011 -0.00000000 -0.00 -0.02 -0.00<br>
-0.00000013 -0.00000000 0.00000011 -0.02 -0.00 0.02<br>
</p><p>
<br>
</p>
<p>
and the output stress from scf:
</p>
<p>
</p><div>
total stress (Ry/bohr**3) (kbar) P= -417.74
</div>
<p>
-0.00286693 0.00000000 -0.00006361 -421.74 0.00 -9.36<br>
0.00000000 -0.00279769 0.00000000 0.00 -411.55 0.00<br>
-0.00006361 0.00000000 -0.00285453 -9.36 0.00 -419.92<br>
</p><div>
<br>
</div>
<p>
<br>
</p>
<p>
The input files for vc-relax is as below:
</p>
<p>
</p><p style="font-family:SimSun;white-space:normal;">
---------------start of vc-relax.in---------------------
</p>
<p></p>
<p>
<span style="font-family:SimSun;">&CONTROL</span><br>
<span style="font-family:SimSun;">calculation = 'vc-relax'</span><br>
<span style="font-family:SimSun;">verbosity = 'high'</span><br>
<span style="font-family:SimSun;">restart_mode = 'from_scratch'</span><br>
<span style="font-family:SimSun;">wf_collect = .true.</span><br>
<span style="font-family:SimSun;">nstep = 200</span><br>
<span style="font-family:SimSun;">tstress = .true.</span><br>
<span style="font-family:SimSun;">tprnfor = .true.</span><br>
<span style="font-family:SimSun;">outdir = './'</span><br>
<span style="font-family:SimSun;">prefix = 'NiP2-monoclinic'</span><br>
<span style="font-family:SimSun;">etot_conv_thr = 1.0D-6</span><br>
<span style="font-family:SimSun;">forc_conv_thr = 1.0D-5</span><br>
<span style="font-family:SimSun;">pseudo_dir = '../../pp/'</span><br>
<span style="font-family:SimSun;">!tefield = .true. !add saw-like potential</span><br>
<span style="font-family:SimSun;">!dipfield = .true.</span><br>
<span style="font-family:SimSun;">!lelfield = .true.</span><br>
<span style="font-family:SimSun;">!nberrycyc = 5</span><br>
<span style="font-family:SimSun;">!gdir = 3</span><br>
<span style="font-family:SimSun;">!nppstr = 1</span><br>
<span style="font-family:SimSun;">/</span><br>
<span style="font-family:SimSun;">&SYSTEM</span><br>
<span style="font-family:SimSun;">ibrav = 0</span><br>
<span style="font-family:SimSun;">celldm(1) = 1.6896</span><br>
<span style="font-family:SimSun;">!celldm(2) =</span><br>
<span style="font-family:SimSun;">!celldm(3) = 9.5983431328106</span><br>
<span style="font-family:SimSun;">nat = 12</span><br>
<span style="font-family:SimSun;">ntyp = 2</span><br>
<span style="font-family:SimSun;">!nbnd =</span><br>
<span style="font-family:SimSun;">!tot_charge =</span><br>
<span style="font-family:SimSun;">!tot_magnetization = </span><br>
<span style="font-family:SimSun;">!starting_magnetization(1) = </span><br>
<span style="font-family:SimSun;">!angle1(1) = </span><br>
<span style="font-family:SimSun;">!angle2(1) =</span><br>
<span style="font-family:SimSun;">ecutwfc = 120</span><br>
<span style="font-family:SimSun;">ecutrho = 480 !if ncpp,stick to the 4* relation </span><br>
<span style="font-family:SimSun;">!nr1 =</span><br>
<span style="font-family:SimSun;">!nr2 =</span><br>
<span style="font-family:SimSun;">!nr3 =</span><br>
<span style="font-family:SimSun;">!nosym = .true.</span><br>
<span style="font-family:SimSun;">!noinv = .true.</span><br>
<span style="font-family:SimSun;">!no_t_rev = .true. ! disable the usage of magnetic symmetry operations</span><br>
<span style="font-family:SimSun;">!occupations = 'fixed' ! set to 'tetrahedra' if calculate dos</span><br>
<span style="font-family:SimSun;"> occupations = 'smearing'</span><br>
<span style="font-family:SimSun;"> smearing = 'gaussian'</span><br>
<span style="font-family:SimSun;">degauss = 0.01 ! check the smearing contribution to total energy and if it </span><br>
<span style="font-family:SimSun;"> ! is large then try to lower the value</span><br>
<span style="font-family:SimSun;">nspin = 1 ! 1:non-polarized 2: magnetization along z axis</span><br>
<span style="font-family:SimSun;"><br>
</span><br>
<span style="font-family:SimSun;">!noncolin = .true. ! magnetization in generic direction,</span><br>
<span style="font-family:SimSun;">!lspinorb = .true. ! soc calculation use a pseudopotential with spin-orbit.</span><br>
<span style="font-family:SimSun;">!assume_isolated= '2D'</span><br>
<span style="font-family:SimSun;">!input_dft = 'vdW-DF' ! defining the DFT functional</span><br>
<span style="font-family:SimSun;">!nqx1 = 1 ! proportional to nk1; for hybrid functions</span><br>
<span style="font-family:SimSun;">!nqx2 = 1 ! proportional to nk2</span><br>
<span style="font-family:SimSun;">!nqx3 = 1 ! proportional to nk3</span><br>
<span style="font-family:SimSun;">!lda_plus_u = .true.</span><br>
<span style="font-family:SimSun;">!Hubbard_U(1) = 0</span><br>
<span style="font-family:SimSun;">!Hubbard_U(2) = 0</span><br>
<span style="font-family:SimSun;">!vdw_corr = 'DFT-D' ! Dispersion correction in vdw calculations</span><br>
<span style="font-family:SimSun;"><br>
</span><br>
<span style="font-family:SimSun;">!edir = 3 ! This is the direction of applied field</span><br>
<span style="font-family:SimSun;">!emaxpos = 0.95</span><br>
<span style="font-family:SimSun;">!eopreg = 0.1</span><br>
<span style="font-family:SimSun;">!eamp = 0.019446905 ! Amplitude of e-field 1a.u. = 51.4220632*10^10 V/m</span><br>
<span style="font-family:SimSun;">/</span><br>
<span style="font-family:SimSun;">&ELECTRONS</span><br>
<span style="font-family:SimSun;">electron_maxstep = 1000</span><br>
<span style="font-family:SimSun;">conv_thr = 1.0D-10</span><br>
<span style="font-family:SimSun;">mixing_mode = 'plain'</span><br>
<span style="font-family:SimSun;">!mixing_mode = 'local-TF'</span><br>
<span style="font-family:SimSun;">mixing_beta = 0.5</span><br>
<span style="font-family:SimSun;">diagonalization = 'david'</span><br>
<span style="font-family:SimSun;">!diago_thr_init = 1.0D-13 ! for non-scf calculations</span><br>
<span style="font-family:SimSun;">!diago_full_acc = .true.</span><br>
<span style="font-family:SimSun;">!efield = 0.027502070 ! 1 a.u. = 36.3609*10^10 V/m</span><br>
<span style="font-family:SimSun;">!efield_cart(1) = 0.0</span><br>
<span style="font-family:SimSun;">!efield_cart(2) = 0.0 </span><br>
<span style="font-family:SimSun;">!efield_cart(3) = 0.027502070</span><br>
<span style="font-family:SimSun;">!startingpot = 'file' !start from existing charge file</span><br>
<span style="font-family:SimSun;">!startingwfc = 'file'</span><br>
<span style="font-family:SimSun;">/</span><br>
<span style="font-family:SimSun;">&IONS</span><br>
<span style="font-family:SimSun;">ion_dynamics = 'bfgs'</span><br>
<span style="font-family:SimSun;">upscale = 1.0D3</span><br>
<span style="font-family:SimSun;">trust_radius_min = 1.0D-15</span><br>
<span style="font-family:SimSun;">/</span><br>
<span style="font-family:SimSun;">&CELL</span><br>
<span style="font-family:SimSun;">cell_dynamics = 'bfgs'</span><br>
<span style="font-family:SimSun;">press = 0</span><br>
<span style="font-family:SimSun;">press_conv_thr = 0.01</span><br>
<span style="font-family:SimSun;">cell_dofree = 'all'</span><br>
<span style="font-family:SimSun;">/</span><br>
<span style="font-family:SimSun;">CELL_PARAMETERS {alat}</span><br>
<span style="font-family:SimSun;"> 6.210735282 -0.000000003 -0.228119407</span><br>
<span style="font-family:SimSun;"> -0.000000002 5.833791719 -0.000000015</span><br>
<span style="font-family:SimSun;"> -2.783178192 -0.000000013 5.154174308</span><br>
<span style="font-family:SimSun;">ATOMIC_SPECIES</span><br>
<span style="font-family:SimSun;">P 30.9737 P.pz-hgh.UPF</span><br>
<span style="font-family:SimSun;">Ni 58.6934 Ni.pz-hgh.UPF</span><br>
<span style="font-family:SimSun;">ATOMIC_POSITIONS {crystal}</span><br>
<span style="font-family:SimSun;">P 0.2206418181 0.1125023368 0.3445362239</span><br>
<span style="font-family:SimSun;">P 0.7793582199 0.8874976832 0.6554637631</span><br>
<span style="font-family:SimSun;">P 0.7793582103 0.1125022767 0.1554637796</span><br>
<span style="font-family:SimSun;">P 0.2206418107 0.8874977433 0.8445362534</span><br>
<span style="font-family:SimSun;">P 0.7206419422 0.6125043167 0.3445270549</span><br>
<span style="font-family:SimSun;">P 0.2793580398 0.3874957243 0.6554729321</span><br>
<span style="font-family:SimSun;">P 0.2793580310 0.6125043756 0.1554729615</span><br>
<span style="font-family:SimSun;">P 0.7206419340 0.3874956654 0.8445270715</span><br>
<span style="font-family:SimSun;">Ni 0.2499621059 0.2500045449 -0.0000154609</span><br>
<span style="font-family:SimSun;">Ni 0.7500379121 0.7499954551 0.0000154609</span><br>
<span style="font-family:SimSun;">Ni 0.7500378821 0.2500044729 0.5000154429</span><br>
<span style="font-family:SimSun;">Ni 0.2499621649 0.7499955271 0.4999845671</span><br>
<span style="font-family:SimSun;">K_POINTS {automatic} !50 ! if molecular {gamma}</span><br>
<span style="font-family:SimSun;">8 8 8 0 0 0</span><br>
</p><div style="font-family:SimSun;white-space:nowrap;">
---------------end of vc-relax.in---------------------
</div>
<p></p>
<p></p>
<p></p>
<p></p>
<p style="font-family:SimSun;">
And the scf input is as follows,
</p>
<p style="font-family:SimSun;">
--------start of scf.in----------
</p>
<p style="font-family:SimSun;">
&CONTROL<br>
calculation = 'scf'<br>
!verbosity = 'high'<br>
restart_mode = 'from_scratch'<br>
wf_collect = .true.<br>
nstep = 200<br>
tstress = .true.<br>
tprnfor = .true.<br>
outdir = './'<br>
prefix = 'NiP2-monoclinic'<br>
etot_conv_thr = 1.0D-6<br>
forc_conv_thr = 1.0D-5<br>
pseudo_dir = '../../pp/'<br>
!tefield = .true. !add saw-like potential<br>
!dipfield = .true.<br>
!lelfield = .true.<br>
!nberrycyc = 5<br>
!gdir = 3<br>
!nppstr = 1<br>
/<br>
&SYSTEM<br>
ibrav = 0<br>
celldm(1) = 1.88964475<br>
!celldm(2) =<br>
!celldm(3) = 9.5983431328106<br>
nat = 12<br>
ntyp = 2<br>
!nbnd =<br>
!tot_charge =<br>
!tot_magnetization = <br>
!starting_magnetization(1) = <br>
!angle1(1) = <br>
!angle2(1) =<br>
ecutwfc = 120<br>
ecutrho = 480 !if ncpp,stick to the 4* relation <br>
!nr1 =<br>
!nr2 =<br>
!nr3 =<br>
!nosym = .true.<br>
!noinv = .true.<br>
!no_t_rev = .true. ! disable the usage of magnetic symmetry operations<br>
!occupations = 'fixed' ! set to 'tetrahedra' if calculate dos<br>
occupations = 'smearing'<br>
smearing = 'gaussian'<br>
degauss = 0.01 ! check the smearing contribution to total energy and if it <br>
! is large then try to lower the value<br>
nspin = 1 ! 1:non-polarized 2: magnetization along z axis<br>
<br>
!noncolin = .true. ! magnetization in generic direction,<br>
!lspinorb = .true. ! soc calculation use a pseudopotential with spin-orbit.<br>
!assume_isolated= '2D'<br>
!input_dft = 'vdW-DF' ! defining the DFT functional<br>
!nqx1 = 1 ! proportional to nk1; for hybrid functions<br>
!nqx2 = 1 ! proportional to nk2<br>
!nqx3 = 1 ! proportional to nk3<br>
!lda_plus_u = .true.<br>
!Hubbard_U(1) = 0<br>
!Hubbard_U(2) = 0<br>
!vdw_corr = 'DFT-D' ! Dispersion correction in vdw calculations<br>
<br>
!edir = 3 ! This is the direction of applied field<br>
!emaxpos = 0.95<br>
!eopreg = 0.1<br>
!eamp = 0.019446905 ! Amplitude of e-field 1a.u. = 51.4220632*10^10 V/m<br>
/<br>
&ELECTRONS<br>
electron_maxstep = 1000<br>
conv_thr = 1.0D-10<br>
mixing_mode = 'plain'<br>
!mixing_mode = 'local-TF'<br>
mixing_beta = 0.5<br>
diagonalization = 'david'<br>
!diago_thr_init = 1.0D-13 ! for non-scf calculations<br>
!diago_full_acc = .true.<br>
!efield = 0.027502070 ! 1 a.u. = 36.3609*10^10 V/m<br>
!efield_cart(1) = 0.0<br>
!efield_cart(2) = 0.0 <br>
!efield_cart(3) = 0.027502070<br>
!startingpot = 'file' !start from existing charge file<br>
!startingwfc = 'file'<br>
/<br>
CELL_PARAMETERS {alat}<br>
6.2577067603003895 0.0000000000000000 -0.0777025195301591<br>
0.0000000000000000 5.5251065872474996 0.0000000000000000<br>
-2.6753479058107592 0.0000000000000000 4.8473353267277162<br>
ATOMIC_SPECIES<br>
P 30.9737 P.pz-hgh.UPF<br>
Ni 58.6934 Ni.pz-hgh.UPF<br>
ATOMIC_POSITIONS (crystal)<br>
P 0.2015645274872214 0.1129918772500652 0.3353648698544600<br>
P 0.7984355105127818 0.8870081427499362 0.6646351171455352<br>
P 0.7984354965127807 0.1129918772500652 0.1646351351455369<br>
P 0.2015645244872176 0.8870081427499362 0.8353648978544624<br>
P 0.7015644904872218 0.6129918982500636 0.3353648698544600<br>
P 0.2984354915127767 0.3870081427499364 0.6646351171455352<br>
P 0.2984354775127825 0.6129918982500636 0.1646351351455369<br>
P 0.7015644874872180 0.3870081427499364 0.8353648978544624<br>
Ni 0.2500000000000000 0.2500000000000000 -0.0000000000000000<br>
Ni 0.7500000180000015 0.7500000000000000 -0.0000000000000000<br>
Ni 0.7500000420000035 0.2500000000000000 0.5000000049999969<br>
Ni 0.2500000049999969 0.7500000000000000 0.5000000049999969<br>
K_POINTS {automatic} !50 ! if molecular {gamma}<br>
8 8 8 0 0 0<span style="white-space:nowrap;"></span>
</p>
<p style="font-family:SimSun;">
--------end of scf.in------------
</p>