Dear QE, We are trying to determine the stability of monolayer black phosphorous using molecular dynamics with nose thermostat as implemented in cp.x. However,even at very high temperature(around 5000K), the structure does not melt though there are significant vibrations.
Kindly inform us whether the issue is associated with the nose frequency, the initial random displacement, emass chosen or any other parameter. We followed the procedures given in the cp.x user guide : http://www.quantum-espresso.org/wp-content/uploads/Doc/cp_user_guide.pdf We appreciate your replies with gratitude... Barun Ghosh PhD Student Dept of Physics IIT Kanpur The input files are as follows: STEP 1 ( Determining Electronic ground state - I) &control calculation='cp', restart_mode='from_scratch', nstep=200, iprint=20, isave=20, dt=5, ndr=90, ndw=91, pseudo_dir='/home/barung/espresso/upf_files', outdir='./output/', / &SYSTEM ibrav = 0, celldm(1) = 1.889725989, nat = 36, ntyp = 1, ecutwfc = 120, ecfixed = 14.0, qcutz = 14.0, q2sigma = 2.0 / &electrons electron_dynamics='damp', electron_damping=0.1, startingwfc='random', ampre=0.01, orthogonalization='Gram-Schmidt', emass=50, emass_cutoff=3., / &ions ion_radius(1)=1.0, ion_dynamics='none' / ATOMIC_SPECIES P 31.0 P.pbe-mt_fhi.UPF ATOMIC_POSITIONS (angstrom) P 0.4145944110 -1.6527352540 7.9416845570 P 0.4145944110 -4.9582057620 7.9416845570 P 0.4145944110 -8.2636762700 7.9416845570 P 11.1298393070 -3.3054705080 7.9501494580 P 11.1298393070 -6.6109410160 7.9501494580 P 11.1298393070 -9.9164115240 7.9501494580 P 11.9448235830 -3.3054705080 10.0578357590 P 11.9448235830 -6.6109410160 10.0578357590 P 11.9448235830 -9.9164115240 10.0578357590 P 13.4328383110 -1.6527352540 10.0541393780 P 13.4328383110 -4.9582057620 10.0541393780 P 13.4328383110 -8.2636762700 10.0541393780 P 1.9026219450 -3.3054705080 7.9467507480 P 1.9026219450 -6.6109410160 7.9467507480 P 1.9026219450 -9.9164115240 7.9467507480 P 2.7176062210 -3.3054705080 10.0544370490 P 2.7176062210 -6.6109410160 10.0544370490 P 2.7176062210 -9.9164115240 10.0544370490 P 4.2056209490 -1.6527352540 10.0507406680 P 4.2056209490 -4.9582057620 10.0507406680 P 4.2056209490 -8.2636762700 10.0507406680 P 5.0282030920 -1.6527352540 7.9433839120 P 5.0282030920 -4.9582057620 7.9433839120 P 5.0282030920 -8.2636762700 7.9433839120 P 6.5162306260 -3.3054705080 7.9484501030 P 6.5162306260 -6.6109410160 7.9484501030 P 6.5162306260 -9.9164115240 7.9484501030 P 7.3312149020 -3.3054705080 10.0561364040 P 7.3312149020 -6.6109410160 10.0561364040 P 7.3312149020 -9.9164115240 10.0561364040 P 8.8192296300 -1.6527352540 10.0524400230 P 8.8192296300 -4.9582057620 10.0524400230 P 8.8192296300 -8.2636762700 10.0524400230 P 9.6418117730 -1.6527352540 7.9450832670 P 9.6418117730 -4.9582057620 7.9450832670 P 9.6418117730 -8.2636762700 7.9450832670 CELL_PARAMETERS 0.0000000000 -9.9164115240 0.0000000000 13.8408260430 0.0000000000 0.0050980650 0.0073478690 0.0000000000 19.9945635070 STEP 2 ( Determining Electronic ground state - II ) &control calculation='cp', restart_mode='restart', nstep=400, iprint=10, isave=50, dt=5, ndr=91, ndw=92, pseudo_dir='/home/barung/espresso/upf_files', outdir='./output/', etot_conv_thr=1.e-6 / &SYSTEM ibrav = 0, nat = 36, celldm(1) = 1.889725989, ntyp = 1, ecutwfc = 120, ecfixed = 14.0, qcutz = 14.0, q2sigma = 2.0 / &electrons electron_dynamics='damp', electron_damping=2.0, emass=100, emass_cutoff=3., / &ions ion_radius(1)=1.0, ion_dynamics='none' / ATOMIC_SPECIES P 31.0 P.pbe-mt_fhi.UPF ATOMIC_POSITIONS (angstrom) P 0.4145944110 -1.6527352540 7.9416845570 P 0.4145944110 -4.9582057620 7.9416845570 P 0.4145944110 -8.2636762700 7.9416845570 P 11.1298393070 -3.3054705080 7.9501494580 P 11.1298393070 -6.6109410160 7.9501494580 P 11.1298393070 -9.9164115240 7.9501494580 P 11.9448235830 -3.3054705080 10.0578357590 P 11.9448235830 -6.6109410160 10.0578357590 P 11.9448235830 -9.9164115240 10.0578357590 P 13.4328383110 -1.6527352540 10.0541393780 P 13.4328383110 -4.9582057620 10.0541393780 P 13.4328383110 -8.2636762700 10.0541393780 P 1.9026219450 -3.3054705080 7.9467507480 P 1.9026219450 -6.6109410160 7.9467507480 P 1.9026219450 -9.9164115240 7.9467507480 P 2.7176062210 -3.3054705080 10.0544370490 P 2.7176062210 -6.6109410160 10.0544370490 P 2.7176062210 -9.9164115240 10.0544370490 P 4.2056209490 -1.6527352540 10.0507406680 P 4.2056209490 -4.9582057620 10.0507406680 P 4.2056209490 -8.2636762700 10.0507406680 P 5.0282030920 -1.6527352540 7.9433839120 P 5.0282030920 -4.9582057620 7.9433839120 P 5.0282030920 -8.2636762700 7.9433839120 P 6.5162306260 -3.3054705080 7.9484501030 P 6.5162306260 -6.6109410160 7.9484501030 P 6.5162306260 -9.9164115240 7.9484501030 P 7.3312149020 -3.3054705080 10.0561364040 P 7.3312149020 -6.6109410160 10.0561364040 P 7.3312149020 -9.9164115240 10.0561364040 P 8.8192296300 -1.6527352540 10.0524400230 P 8.8192296300 -4.9582057620 10.0524400230 P 8.8192296300 -8.2636762700 10.0524400230 P 9.6418117730 -1.6527352540 7.9450832670 P 9.6418117730 -4.9582057620 7.9450832670 P 9.6418117730 -8.2636762700 7.9450832670 CELL_PARAMETERS 0.0000000000 -9.9164115240 0.0000000000 13.8408260430 0.0000000000 0.0050980650 0.0073478690 0.0000000000 19.9945635070 STEP 3 ( Random displacement of atoms from their equilibrium position ) &control calculation='cp', restart_mode='reset_counters', nstep=4000, iprint=10, isave=100, dt=3.0, disk_io='high' ndr=92, ndw=931, pseudo_dir='/home/barung/espresso/upf_files', outdir='./output/', / &SYSTEM ibrav = 0, celldm(1) = 1.889725989, nat = 36, ntyp = 1, ecutwfc = 120, ecfixed = 14.0, qcutz = 14.0, q2sigma = 2.0 / &electrons electron_dynamics='damp', ortho_max=100, emass=100, emass_cutoff=3., / &ions ion_dynamics='none', ion_radius(1)=1.0 tranp(1)=.TRUE. tranp(2)=.TRUE. amprp(1)=0.01 amprp(2)=0.01 / ATOMIC_SPECIES P 31.0 P.pbe-mt_fhi.UPF ATOMIC_POSITIONS (angstrom) P 0.4145944110 -1.6527352540 7.9416845570 P 0.4145944110 -4.9582057620 7.9416845570 P 0.4145944110 -8.2636762700 7.9416845570 P 11.1298393070 -3.3054705080 7.9501494580 P 11.1298393070 -6.6109410160 7.9501494580 P 11.1298393070 -9.9164115240 7.9501494580 P 11.9448235830 -3.3054705080 10.0578357590 P 11.9448235830 -6.6109410160 10.0578357590 P 11.9448235830 -9.9164115240 10.0578357590 P 13.4328383110 -1.6527352540 10.0541393780 P 13.4328383110 -4.9582057620 10.0541393780 P 13.4328383110 -8.2636762700 10.0541393780 P 1.9026219450 -3.3054705080 7.9467507480 P 1.9026219450 -6.6109410160 7.9467507480 P 1.9026219450 -9.9164115240 7.9467507480 P 2.7176062210 -3.3054705080 10.0544370490 P 2.7176062210 -6.6109410160 10.0544370490 P 2.7176062210 -9.9164115240 10.0544370490 P 4.2056209490 -1.6527352540 10.0507406680 P 4.2056209490 -4.9582057620 10.0507406680 P 4.2056209490 -8.2636762700 10.0507406680 P 5.0282030920 -1.6527352540 7.9433839120 P 5.0282030920 -4.9582057620 7.9433839120 P 5.0282030920 -8.2636762700 7.9433839120 P 6.5162306260 -3.3054705080 7.9484501030 P 6.5162306260 -6.6109410160 7.9484501030 P 6.5162306260 -9.9164115240 7.9484501030 P 7.3312149020 -3.3054705080 10.0561364040 P 7.3312149020 -6.6109410160 10.0561364040 P 7.3312149020 -9.9164115240 10.0561364040 P 8.8192296300 -1.6527352540 10.0524400230 P 8.8192296300 -4.9582057620 10.0524400230 P 8.8192296300 -8.2636762700 10.0524400230 P 9.6418117730 -1.6527352540 7.9450832670 P 9.6418117730 -4.9582057620 7.9450832670 P 9.6418117730 -8.2636762700 7.9450832670 CELL_PARAMETERS 0.0000000000 -9.9164115240 0.0000000000 13.8408260430 0.0000000000 0.0050980650 0.0073478690 0.0000000000 19.9945635070 STEP 4 ( Molecular Dynamics using nose thermostat ) &control calculation='cp', restart_mode='reset_counters', nstep=60000, iprint=10, isave=100, dt=3.0, ndr=92, ndw=932, pseudo_dir='/home/barung/espresso/upf_files', outdir='./output/', disk_io='high' / &SYSTEM ibrav = 0, nat = 36, ntyp = 1, celldm(1) = 1.889725989, ecutwfc = 120, ecfixed = 14.0, qcutz = 14.0, q2sigma = 2.0 / &electrons electron_dynamics='damp', ortho_max=100, emass=100, emass_cutoff=3., / &ions ion_dynamics='verlet', ion_temperature='nose', tempw=4800, fnosep=20, ion_radius(1)=1.0, / ATOMIC_SPECIES P 31.0 P.pbe-mt_fhi.UPF ATOMIC_POSITIONS (angstrom) P 0.4145944110 -1.6527352540 7.9416845570 P 0.4145944110 -4.9582057620 7.9416845570 P 0.4145944110 -8.2636762700 7.9416845570 P 11.1298393070 -3.3054705080 7.9501494580 P 11.1298393070 -6.6109410160 7.9501494580 P 11.1298393070 -9.9164115240 7.9501494580 P 11.9448235830 -3.3054705080 10.0578357590 P 11.9448235830 -6.6109410160 10.0578357590 P 11.9448235830 -9.9164115240 10.0578357590 P 13.4328383110 -1.6527352540 10.0541393780 P 13.4328383110 -4.9582057620 10.0541393780 P 13.4328383110 -8.2636762700 10.0541393780 P 1.9026219450 -3.3054705080 7.9467507480 P 1.9026219450 -6.6109410160 7.9467507480 P 1.9026219450 -9.9164115240 7.9467507480 P 2.7176062210 -3.3054705080 10.0544370490 P 2.7176062210 -6.6109410160 10.0544370490 P 2.7176062210 -9.9164115240 10.0544370490 P 4.2056209490 -1.6527352540 10.0507406680 P 4.2056209490 -4.9582057620 10.0507406680 P 4.2056209490 -8.2636762700 10.0507406680 P 5.0282030920 -1.6527352540 7.9433839120 P 5.0282030920 -4.9582057620 7.9433839120 P 5.0282030920 -8.2636762700 7.9433839120 P 6.5162306260 -3.3054705080 7.9484501030 P 6.5162306260 -6.6109410160 7.9484501030 P 6.5162306260 -9.9164115240 7.9484501030 P 7.3312149020 -3.3054705080 10.0561364040 P 7.3312149020 -6.6109410160 10.0561364040 P 7.3312149020 -9.9164115240 10.0561364040 P 8.8192296300 -1.6527352540 10.0524400230 P 8.8192296300 -4.9582057620 10.0524400230 P 8.8192296300 -8.2636762700 10.0524400230 P 9.6418117730 -1.6527352540 7.9450832670 P 9.6418117730 -4.9582057620 7.9450832670 P 9.6418117730 -8.2636762700 7.9450832670 CELL_PARAMETERS 0.0000000000 -9.9164115240 0.0000000000 13.8408260430 0.0000000000 0.0050980650 0.0073478690 0.0000000000 19.9945635070 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
