<div dir="ltr">Dear All, I am running a NVT MD simulation on MgSiO3 (250 atoms) at high pressure and temperature by cp2k2.7 on ARCHER. The problem is relating to TIMESTEP. Because it is a high pressure and temperature simulation, so I try different TIMESTEP = 0.5 fs, 0.75 fs, 1.0 fs, 1.5 fs, 2.0 fs to run MD simulation. 0.5 fs, 1.5 fs, and 2.0 fs works well. But 0.75 fs, and 1 fs don't work, crash at thousand steps because reaching the max SCF cycles. Even though I restart it, it will crash in a few of steps. Could anyone tell me if I got anything wrong? I prefer to use 1 fs, but doesn't work. Thanks. I pasted input file and bottom of .ener .stress and output file here. Regards, Tao 'input file' <a href="https://en.wikipedia.org/wiki/Car%E2%80%93Parrinello_molecular_dynamics#cite_note-3" target="_blank"></a>&GLOBAL PROJECT pv-lad RUN_TYPE md PRINT_LEVEL low &END GLOBAL &MOTION &PRINT &STRESS &END STRESS &velocities &end velocities &END PRINT &MD ENSEMBLE NVT STEPS 5000 TIMESTEP 1 TEMPERATURE 4000.0 &THERMOSTAT &NOSE LENGTH 3 YOSHIDA 3 TIMECON 10.0 MTS 2 &END NOSE &END &END MD &END MOTION &FORCE_EVAL METHOD Quickstep STRESS_TENSOR analytical &DFT BASIS_SET_FILE_NAME BASIS_MOLOPT POTENTIAL_FILE_NAME POTENTIAL &MGRID CUTOFF 500 REL_CUTOFF 40 &END MGRID &PRINT &DFT_CONTROL_PARAMETERS &END DFT_CONTROL_PARAMETERS &END PRINT &QS ls_scf EPS_DEFAULT 1.0E-10 EXTRAPOLATION use_prev_p MAP_CONSISTENT &END QS &LS_SCF PURIFICATION_METHOD TRS4 MU 0.15 MAX_SCF 200 S_PRECONDITIONER ATOMIC &END &SCF &OT ON MIXED_PRECISION .TRUE. &END OT EPS_SCF 1.0E-5 MAX_SCF 200 SCF_GUESS atomic &OUTER_SCF EPS_SCF 1.0E-7 MAX_SCF 500 &END &END SCF &XC &XC_FUNCTIONAL LDA &END XC_FUNCTIONAL &END XC &END DFT &PRINT &STRESS_TENSOR NDIGITS 4 &END STRESS_TENSOR &END PRINT &SUBSYS &CELL ABC 26.0369999999999990 9.1050000000000004 6.2900000000000000 MULTIPLE_UNIT_CELL 1 1 1 SYMMETRY ORTHORHOMBIC &END CELL &COORD Mg 0.0835357257057528 0.2080505102144339 0.7695373512802808 Mg 0.4168690590390862 0.2080505102144339 0.7695373512802808 ... ... ... ... ... SCALED T &END COORD &TOPOLOGY MULTIPLE_UNIT_CELL 1 1 1 &END TOPOLOGY &KIND Mg BASIS_SET DZVP-MOLOPT-SR-GTH POTENTIAL GTH-PADE-q10 &END KIND &KIND Si BASIS_SET DZVP-MOLOPT-SR-GTH POTENTIAL GTH-PADE-q4 &END KIND &KIND O BASIS_SET DZVP-MOLOPT-SR-GTH POTENTIAL GTH-PADE-q6 &END KIND &PRINT &CELL &END CELL &KINDS BASIS_SET POTENTIAL &END KINDS &END PRINT &END SUBSYS &END FORCE_EVAL '*.ener' 52241 99241.000000 4.411213874 3885.493746208 -5533.754419320 -5511.857390810 25.345344531 52242 99242.000000 4.342485222 3824.956044365 -5533.605897687 -5511.856215770 18.092279346 52243 99243.000000 4.276184769 3766.557154129 -5533.468202487 -5511.855599935 13.521783815 52244 99244.000000 4.219259478 3716.416111920 -5533.347713891 -5511.855260868 20.452569381 52245 99245.000000 4.174711953 3677.177676762 -5533.244993727 -5511.854024077 13.410673904 52246 99246.000000 4.157625727 3662.127754916 -5533.174592854 -5511.853076546 18.038370990 52247 99247.000000 4.175426934 3677.807447113 -5533.137836015 -5511.847932992 13.264672622 52248 99248.000000 NaN NaN 156032.896882306 NaN 575.632388886 '*.stress' 52241 99241.000 1393467.1901913243 -4049.0319591435 16542.2251158790 -4049.0319591435 1342881.5952529698 6198.4426952424 16542.2251158790 6198.4426952424 1366629.9398137301 52242 99242.000 1397547.5508231323 -4579.9413527279 13810.5798040272 -4579.9413527279 1347383.1869124325 4835.2659481228 13810.5798040272 4835.2659481228 1367257.9328355824 52243 99243.000 1402562.0095211340 -2469.8827275863 11326.0268584547 -2469.8827275863 1355053.6419066861 2967.7081481965 11326.0268584547 2967.7081481965 1368330.4512780211 52244 99244.000 1408171.8438126745 888.5049041032 7965.5485159208 888.5049041032 1364397.2652421803 822.2322445308 7965.5485159208 822.2322445308 1372140.1351925349 52245 99245.000 1409730.5634058635 5552.5388752075 4525.6394441786 5552.5388752075 1370727.1093890155 -1862.2415766141 4525.6394441786 -1862.2415766141 1376614.3797829675 52246 99246.000 1412460.3088731237 9057.5282769796 628.5805615638 9057.5282769796 1378499.6190023583 -4538.0776370565 628.5805615638 -4538.0776370565 1383519.0328408128 52247 99247.000 1411091.8367309219 13731.7124595861 -2346.7333744248 13731.7124595861 1387502.2123396317 -7483.0678576032 -2346.7333744248 -7483.0678576032 1382544.9170446743 52248 99248.000 NaN NaN NaN NaN NaN NaN NaN NaN NaN '.out' SCF 198 158962.937507772 1965.560497129 2.771007 ********************************************************* Using MIXING_FRACTION=0.450 to mix KS matrix: iscf=199 KS_nw=0.450*KS + 0.550*KS_old ********************************************************* Lanczos converged: F change in mixed matrix: 141.05387 HOMO upper bound: 104.64941 LUMO lower bound: -177.33021 Predicts a gap ? F Est. extremal eigenvalues -69.03105 87.29441 converged: F TRS4 it 1 1.00000000 0.897E+02 0.047 4763.272 0.100E-05 TRS4 it 2 1.00000000 0.857E+02 0.052 4321.115 0.100E-05 TRS4 it 3 1.00000000 0.635E+02 0.094 4126.422 0.100E-05 TRS4 it 4 1.00000000 0.439E+02 0.087 4013.760 0.100E-05 TRS4 it 5 0.96654122 0.289E+02 0.090 3488.278 0.100E-05 TRS4 it 6 0.95568580 0.191E+02 0.078 3775.442 0.100E-05 TRS4 it 7 0.95672906 0.125E+02 0.082 3520.711 0.100E-05 TRS4 it 8 0.96273637 0.816E+01 0.081 3564.536 0.100E-05 TRS4 it 9 0.98135529 0.537E+01 0.078 3735.249 0.100E-05 TRS4 it 10 0.98941451 0.355E+01 0.080 3692.521 0.100E-05 TRS4 it 11 0.99104224 0.234E+01 0.076 3897.213 0.100E-05 TRS4 it 12 0.99253780 0.154E+01 0.077 3886.772 0.100E-05 TRS4 it 13 0.99272503 0.102E+01 0.078 3853.237 0.100E-05 TRS4 it 14 0.99881619 0.707E+00 0.078 3893.548 0.100E-05 TRS4 it 15 0.99760219 0.494E+00 0.078 3867.742 0.100E-05 TRS4 it 16 0.99128755 0.319E+00 0.079 3805.687 0.100E-05 TRS4 it 17 0.98412362 0.194E+00 0.082 3627.809 0.100E-05 TRS4 it 18 0.95759578 0.119E+00 0.078 3733.491 0.100E-05 TRS4 it 19 0.96372829 0.735E-01 0.077 3804.604 0.100E-05 TRS4 it 20 0.98971046 0.351E-01 0.080 3743.113 0.100E-05 TRS4 it 21 0.99122111 0.764E-02 0.078 3818.051 0.100E-05 TRS4 it 22 0.99122111 0.275E-03 0.079 3795.518 0.100E-05 Final TRS4 iteration 22 0.99122111 0.275E-03 Chemical potential (mu): -37.10018 Lanczos converged: F Lanczos converged: F HOMO/LUMO/gap -37.15175 -36.90884 0.24291 SCF 199 157261.886998689 -1701.050509083 2.799975 ********************************************************* Using MIXING_FRACTION=0.450 to mix KS matrix: iscf=200 KS_nw=0.450*KS + 0.550*KS_old ********************************************************* Lanczos converged: F change in mixed matrix: 139.91979 HOMO upper bound: 102.76805 LUMO lower bound: -176.82863 Predicts a gap ? F Est. extremal eigenvalues -68.87729 85.63565 converged: F TRS4 it 1 1.00000000 0.905E+02 0.047 4789.695 0.100E-05 TRS4 it 2 1.00000000 0.860E+02 0.048 4640.079 0.100E-05 TRS4 it 3 1.00000000 0.629E+02 0.093 4197.692 0.100E-05 TRS4 it 4 0.99871352 0.431E+02 0.084 4141.198 0.100E-05 TRS4 it 5 0.96728110 0.284E+02 0.084 3755.189 0.100E-05 TRS4 it 6 0.95162355 0.186E+02 0.079 3730.035 0.100E-05 TRS4 it 7 0.95464254 0.121E+02 0.077 3690.826 0.100E-05 TRS4 it 8 0.95691490 0.785E+01 0.077 3676.631 0.100E-05 TRS4 it 9 0.96656933 0.508E+01 0.077 3733.906 0.100E-05 TRS4 it 10 0.98102775 0.329E+01 0.080 3647.389 0.100E-05 TRS4 it 11 0.98165356 0.215E+01 0.084 3493.869 0.100E-05 TRS4 it 12 0.98033688 0.142E+01 0.078 3737.030 0.100E-05 TRS4 it 13 0.98043352 0.922E+00 0.082 3590.334 0.100E-05 TRS4 it 14 0.98047952 0.557E+00 0.078 3774.055 0.100E-05 TRS4 it 15 0.98190189 0.302E+00 0.079 3753.784 0.100E-05 TRS4 it 16 0.99003522 0.149E+00 0.080 3713.618 0.100E-05 TRS4 it 17 0.99753877 0.652E-01 0.078 3861.570 0.100E-05 TRS4 it 18 0.99875278 0.190E-01 0.083 3665.070 0.100E-05 TRS4 it 19 0.99753877 0.147E-02 0.080 3805.444 0.100E-05 TRS4 it 20 0.98989026 0.193E-04 0.080 3729.016 0.100E-05 Final TRS4 iteration 20 0.98989026 0.193E-04 Chemical potential (mu): -36.52358 Lanczos converged: F Lanczos converged: F HOMO/LUMO/gap -36.71009 -36.28310 0.42699 SCF 200 156032.896882306 -1228.990116383 2.659866 </div>