Stefano: Hi, here are just some follow ups on the comparison between pwscf and cp.x. Thank you very much for the suggestions, I did vc-relax in cp.x using different size supercells, and just from eyebow, a 2*2*2 supercell already gives considerable agreement with pwscf results. Right now I am quantifying the difference between the lattice structure from cp.x and pw.x by writing a code to calculate Radial Distribution Function.
I have read your papers on Quasi-harmonic phonons and thermal properties calculation, which also helps me understand a lot of concepts in thermal heat transport simulations via DFT. Just want to share my appreciation here.. Thanks for your help. On Thu, Apr 5, 2018 at 2:02 PM, Stefano Baroni <bar...@sissa.it> wrote: > not “unphysical” just inaccurate … SB > > > On 5 Apr 2018, at 19:39, Jie Peng <jiep...@umd.edu> wrote: > > Stefano: > > I think that is right on the spot! Let me do a calculation using Gamma > point only in pwscf and then compare again. > > 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? > > Thank you very much! > > Best > Jie > > On Thu, Apr 5, 2018 at 2:22 AM, Stefano de Gironcoli <degir...@sissa.it> > wrote: > >> Dear Jie Peng, >> >> 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. >> >> I think this is the most relevant difference in your two inputs. >> >> To see if this is the case you can repeat the pw.x calculation with >> >> K_POINT Gamma >> >> Is the 10 8 8 grid really necessary ? is the system metallic ? >> >> 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. >> >> stefano >> >> On 05/04/2018 04:16, Jie Peng wrote: >> >> Dear all Quantum Espresso users: >> >> 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. >> >> *For pwscf simulation, the input file are given below.* >> *&control* >> * calculation='vc-relax',* >> *! restart_mode='from_scratch',* >> * tstress = .true.* >> * tprnfor = .true.* >> >> * wf_collect=.true.* >> * etot_conv_thr=1e-6* >> * forc_conv_thr=1e-5* >> * prefix='Hf',* >> * pseudo_dir='/potential'* >> * outdir='./tmp/',* >> * /* >> * &system* >> * ibrav= 4,* >> * a=3.6529* >> * c=5.6544* >> * nat= 3, ntyp= 2,* >> * ecutwfc =50* >> * vdw_corr='DFT-D',* >> * ! lspinorb=.true.* >> * ! noncolin=.true.* >> * ! ecutrho=300* >> * ! nbnd=14* >> *! occupations='smearing'* >> *! smearing='gaussian'* >> *! degauss=0.01* >> * ! nspin=2* >> * ! starting_magnetization(1)=0.1* >> */* >> * &electrons* >> * conv_thr=1e-12* >> * mixing_beta = 0.7* >> */* >> * &ions* >> * ion_dynamics = 'bfgs'* >> * /* >> * &cell* >> * cell_dynamics = 'bfgs'* >> >> */* >> *ATOMIC_SPECIES* >> * Hf 95.94 Hf.pbe-mt_fhi.UPF* >> * S 32.065 S.pbe-mt_fhi.UPF* >> *ATOMIC_POSITIONS (crystal)* >> *Hf -0.000000000 -0.000000000 -0.000000000* >> *S 0.666666667 0.333333333 0.257234636* >> *S 0.333333333 0.666666667 -0.257234636* >> * K_POINTS automatic* >> *10 8 8 0 0 0* >> >> 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. >> >> * Forces acting on atoms (Ry/au):* >> >> * atom 1 type 1 force = 0.00000000 0.00000000 >> 0.00000000* >> * atom 2 type 2 force = 0.00000000 0.00000000 >> -0.00001404* >> * atom 3 type 2 force = -0.00000000 0.00000000 >> 0.00001404* >> >> * Total force = 0.000020 Total SCF correction = 0.000001* >> >> >> * entering subroutine stress ...* >> >> * total stress (Ry/bohr**3) (kbar) P= >> -0.16* >> * -0.00000129 -0.00000000 0.00000000 -0.19 -0.00 >> 0.00* >> * -0.00000000 -0.00000129 0.00000000 -0.00 -0.19 >> 0.00* >> * 0.00000000 0.00000000 -0.00000078 0.00 0.00 >> -0.12* >> >> *For cp.x, *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. >> >> *Electronic relaxation* >> *&control* >> * calculation='cp',* >> * title='Halfnium disulfide'* >> * restart_mode='from_scratch',* >> * ndr=50,* >> * ndw=50,* >> * nstep=10000,* >> * iprint=100* >> * isave=100,* >> * tstress = .true.* >> * tprnfor = .true.* >> * dt=10,* >> * wf_collect=.true.* >> * etot_conv_thr=1e-6* >> * forc_conv_thr=1e-3* >> * ekin_conv_thr=1e-5* >> * prefix='HfS2',* >> * pseudo_dir='/home/jpeng/HfS2/potential'* >> * outdir='./tmp/',* >> * /* >> * &system* >> * ibrav= 4,* >> * a=3.6529* >> * c=5.6544* >> * nat= 3, ntyp= 2,* >> * ecutwfc =50* >> * vdw_corr='DFT-D',* >> * ! lspinorb=.true.* >> * ! noncolin=.true.* >> * ! ecutrho=300* >> * ! nbnd=14* >> *! occupations='smearing'* >> *! smearing='gaussian'* >> *! degauss=0.01* >> * ! nspin=2* >> * ! starting_magnetization(1)=0.1* >> *! Hf 95.94 Hf.pbe-mt_fhi.UPF* >> *! S 32.065 S.pbe-mt_fhi.UPF* >> */* >> * &electrons* >> * electron_dynamics='damp'* >> *! electron_velocities='zero'* >> * emass=400* >> * emass_cutoff=1* >> * electron_damping=0.1* >> */* >> * &ions* >> * ion_dynamics = 'none'* >> * /* >> * &cell* >> * cell_dynamics = 'none'* >> >> */* >> *ATOMIC_SPECIES* >> * Hf 95.94 Hf.pbe-mt_fhi.UPF* >> * S 32.065 S.pbe-mt_fhi.UPF* >> *ATOMIC_POSITIONS (crystal)* >> *Hf -0.000000000 -0.000000000 -0.000000000* >> *S 0.666666667 0.333333333 0.257234636* >> *S 0.333333333 0.666666667 -0.257234636* >> * K_POINTS automatic* >> *10 8 8 0 0 0* >> >> Ion relaxation >> *&control* >> * calculation='cp',* >> * title='Halfnium disulfide'* >> * restart_mode='restart',* >> * ndr=50,* >> * ndw=51,* >> * nstep=50000,* >> * iprint=100* >> * isave=100,* >> * tstress = .true.* >> * tprnfor = .true.* >> * dt=10,* >> * wf_collect=.true.* >> * etot_conv_thr=1e-6* >> * forc_conv_thr=1e-3* >> * ekin_conv_thr=1e-5* >> * prefix='HfS2',* >> * pseudo_dir='/home/jpeng/HfS2/potential'* >> * outdir='./tmp/',* >> * /* >> * &system* >> * ibrav= 4,* >> * a=3.6529* >> * c=5.6544* >> * nat= 3, ntyp= 2,* >> * ecutwfc =50* >> * vdw_corr='DFT-D',* >> * ! lspinorb=.true.* >> * ! noncolin=.true.* >> * ! ecutrho=300* >> * ! nbnd=14* >> *! occupations='smearing'* >> *! smearing='gaussian'* >> *! degauss=0.01* >> * ! nspin=2* >> * ! starting_magnetization(1)=0.1* >> *! Hf 95.94 Hf.pbe-mt_fhi.UPF* >> *! S 32.065 S.pbe-mt_fhi.UPF* >> */* >> * &electrons* >> * electron_dynamics='damp'* >> *! electron_velocities='zero'* >> * emass=400* >> * emass_cutoff=1* >> * electron_damping=0.1* >> */* >> * &ions* >> * ion_dynamics = 'damp'* >> * ion_damping=0.1* >> * ion_nstepe=10* >> * /* >> * &cell* >> * cell_dynamics = 'none'* >> >> */* >> *ATOMIC_SPECIES* >> * Hf 95.94 Hf.pbe-mt_fhi.UPF* >> * S 32.065 S.pbe-mt_fhi.UPF* >> *ATOMIC_POSITIONS (crystal)* >> *Hf -0.000000000 -0.000000000 -0.000000000* >> *S 0.666666667 0.333333333 0.257234636* >> *S 0.333333333 0.666666667 -0.257234636* >> * K_POINTS automatic* >> *10 8 8 0 0 0* >> >> Cell relaxation >> *&control* >> * calculation='vc-cp',* >> * title='Halfnium disulfide'* >> * restart_mode='reset_counters',* >> * ndr=51,* >> * ndw=52,* >> * nstep=50000,* >> * iprint=100* >> * isave=100,* >> * tstress = .true.* >> * tprnfor = .true.* >> * dt=10,* >> * wf_collect=.true.* >> * etot_conv_thr=1e-6* >> * forc_conv_thr=1e-3* >> * ekin_conv_thr=1e-5* >> * prefix='HfS2',* >> * pseudo_dir='/home/jpeng/HfS2/potential'* >> * outdir='./tmp/',* >> * /* >> * &system* >> * ibrav= 4,* >> * a=3.6529* >> * c=5.6544* >> * nat= 3, ntyp= 2,* >> * ecutwfc =50* >> * vdw_corr='DFT-D',* >> * ! lspinorb=.true.* >> * ! noncolin=.true.* >> * ! ecutrho=300* >> * ! nbnd=14* >> *! occupations='smearing'* >> *! smearing='gaussian'* >> *! degauss=0.01* >> * ! nspin=2* >> * ! starting_magnetization(1)=0.1* >> *! Hf 95.94 Hf.pbe-mt_fhi.UPF* >> *! S 32.065 S.pbe-mt_fhi.UPF* >> */* >> * &electrons* >> * electron_dynamics='damp'* >> *! electron_velocities='zero'* >> * emass=400* >> * emass_cutoff=1* >> * electron_damping=0.1* >> */* >> * &ions* >> * ion_dynamics = 'damp'* >> * ion_damping=0.1* >> * ion_nstepe=10* >> * /* >> * &cell* >> * cell_dynamics = 'pr'* >> *! cell_damping=0.1* >> *! cell_dofree=volume* >> */* >> *ATOMIC_SPECIES* >> * Hf 95.94 Hf.pbe-mt_fhi.UPF* >> * S 32.065 S.pbe-mt_fhi.UPF* >> *ATOMIC_POSITIONS (crystal)* >> *Hf -0.000000000 -0.000000000 -0.000000000* >> *S 0.666666667 0.333333333 0.257234636* >> *S 0.333333333 0.666666667 -0.257234636* >> * K_POINTS automatic* >> *10 8 8 0 0 0* >> >> The final equilibrium lattice structure obtained by cp.x is: >> * CELL_PARAMETERS* >> * 8.27944202 -3.49986616 -1.28541441* >> * 0.43381045 6.25063702 -0.26433640* >> * -1.81611680 -0.30736678 9.28229385* >> >> * System Density [g/cm^3] : 3.7550323993* >> >> >> * System Volume [A.U.^3] : 477.6950599279* >> >> >> * Center of mass square displacement (a.u.): 0.271737* >> >> * Total stress (GPa)* >> * -0.00003957 0.00000336 0.00017132* >> * 0.00000336 -0.00001393 0.00003875* >> * 0.00017132 0.00003875 0.00048005* >> * ATOMIC_POSITIONS* >> * Hf -0.57392945538368E+00 -0.32523714658422E+00 >> -0.78842946683202E-01* >> * S 0.61817237992192E+01 0.34715217744206E+01 >> 0.20852180260292E+00* >> * S 0.31507619982481E+00 0.41860506478142E+01 >> -0.20961035507250E+01* >> >> * ATOMIC_VELOCITIES* >> * Hf -0.49417894612947E-07 -0.41246570825668E-07 >> -0.28182774835127E-06* >> * S 0.29443574450584E-06 0.17988901894696E-06 >> 0.34817154465079E-06* >> * S -0.14657506118618E-06 -0.56477323752712E-07 >> 0.49507043808484E-06* >> >> * Forces acting on atoms (au):* >> * Hf -0.18727766763523E-03 -0.15291863668542E-03 >> -0.99976280595181E-03* >> * S 0.33856074345196E-03 0.20689440901408E-03 >> 0.40153992932368E-03* >> * S -0.17602213243772E-03 -0.68887225779463E-04 >> 0.57298561574671E-03* >> >> A visualization is attached here >> <image.png> >> >> while by pwscf, the equilibrium lattice structure is: >> * CELL_PARAMETERS* >> * 6.90298059 -3.45149030 0.00000000* >> * 0.00000000 5.97815655 0.00000000* >> * 0.00000000 0.00000000 10.68526745* >> >> * System Density [g/cm^3] : 4.0679453101* >> >> >> * System Volume [A.U.^3] : 440.9499858676* >> >> >> * Center of mass square displacement (a.u.): 0.000000* >> >> * Total stress (GPa)* >> * 32.06481501 -0.01335027 -0.00956254* >> * -0.01335027 32.07951164 -0.00592770* >> * -0.00956139 -0.00592704 2.04176052* >> * ATOMIC_POSITIONS* >> * Hf 0.00000000000000E+00 -0.00000000000000E+00 >> -0.00000000000000E+00* >> * S 0.34514902988605E+01 0.19927188491672E+01 >> 0.27486208819801E+01* >> * S -0.34514902047533E-08 0.39854377043125E+01 >> -0.27486208819801E+01* >> >> * ATOMIC_VELOCITIES* >> * Hf 0.00000000000000E+00 0.00000000000000E+00 >> 0.00000000000000E+00* >> * S 0.00000000000000E+00 0.00000000000000E+00 >> 0.00000000000000E+00* >> * S 0.00000000000000E+00 0.00000000000000E+00 >> 0.00000000000000E+00* >> >> * Forces acting on atoms (au):* >> * Hf 0.70847502228925E-03 0.43071957102166E-03 >> -0.17703368862259E-04* >> * S -0.52668423530029E-03 -0.28607208606422E-03 >> -0.81547327015321E-01* >> * S -0.41998284595312E-03 -0.22039679837681E-03 >> 0.81837284893753E-01* >> >> A visulization is attached below >> <image.png> >> >> >> 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. >> >> 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? >> >> Thank you in advance for your help, sincerely! >> >> Best >> Jie >> -- >> ------------------------------------------------------------ >> ------------------------------------------------------------ >> Jie Peng >> PhD student >> 2134 Glenn Martin Hall, Mechanical Engineering, University of Maryland >> College Park, Maryland, USA >> Phone:(+1) 240-495-9445 >> Email: jiep...@umd.edu >> >> >> >> _______________________________________________ >> users mailing >> listusers@lists.quantum-espresso.orghttps://lists.quantum-espresso.org/mailman/listinfo/users >> >> >> >> _______________________________________________ >> users mailing list >> users@lists.quantum-espresso.org >> https://lists.quantum-espresso.org/mailman/listinfo/users >> > > > > -- > ------------------------------------------------------------ > ------------------------------------------------------------ > Jie Peng > PhD student > 2134 Glenn Martin Hall, Mechanical Engineering, University of Maryland > College Park, Maryland, USA > Phone:(+1) 240-495-9445 > Email: jiep...@umd.edu > > _______________________________________________ > users mailing list > users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users > > > > _______________________________________________ > users mailing list > users@lists.quantum-espresso.org > https://lists.quantum-espresso.org/mailman/listinfo/users > -- ------------------------------------------------------------------------------------------------------------------------ Jie Peng PhD student 2134 Glenn Martin Hall, Mechanical Engineering, University of Maryland College Park, Maryland, USA Phone:(+1) 240-495-9445 Email: jiep...@umd.edu
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