Hello Forum, First, thanks very much for the great software package. Here is my issue, one which is probably due to my own ignorance about QE/quantum physics in general:
I'm trying to run a varaible cell relaxation on the compound GeTe. Below is my input file: &control calculation = 'vc-relax' prefix='gt', pseudo_dir = '$HOME/pseudo/', outdir='$HOME/QE/GST/GeTe/out/' forc_conv_thr = 1.0d-5, etot_conv_thr = 1.0d-5, nstep=300, / &system ibrav = 4, celldm(1)=7.993540933, celldm(3)=2.581560284 nat = 18, ntyp= 2, ecutwfc = 100, ecutrho = 800, / &electrons mixing_beta = 0.7 conv_thr = 1.0d-6, / &ions upscale = 100.d0, / &cell cell_dynamics='damp-w' / ATOMIC_SPECIES Te 1.0 Te.pz-bhs.UPF Ge 1.0 Ge.pz-bhs.UPF ATOMIC_POSITIONS {crystal} Te 0 0 0 Ge 0.666666 0.333333 0.055555556 Te 0.33333 0.666666 0.111111111 Ge 0 0 0.166666667 Te 0.6666666 0.3333333 0.222222222 Ge 0.3333333 0.6666666 0.277777778 Te 0 0 0.333333333 Ge 0.6666666 0.3333333 0.388888889 Te 0.3333333 0.6666666 0.444444444 Ge 0 0 0.5 Te 0.6666666 0.3333333 0.555555556 Ge 0.3333333 0.6666666 0.611111111 Te 0 0 0.666666667 Ge 0.6666666 0.3333333 0.722222222 Te 0.3333333 0.6666666 0.777777778 Ge 0 0 0.833333333 Te 0.6666666 0.3333333 0.888888889 Ge 0.3333333 0.6666666 0.944444444 K_POINTS {automatic} 12 12 2 0 0 0 My problem (issue) is this; the simulation continues to time out before completing the relaxation. As such, I've been coninuously increasing the amount of time and processors that I am requesting to perform this calculation. However, it has reached a point (32 processors and 3:30 hours) where I'm almost certain that I am doing something wrong. I was able to find one forum posting where a user was running a relaxation and the calculation was not stopping even though the Energy and Force calculation error thresh holds where being satisfied. It appears that my energy does indeed converge. Let me attach part of my output: ********************************************************************* ! total energy = -203.60367909 Ry Harris-Foulkes estimate = -203.60367961 Ry estimated scf accuracy < 0.00000054 Ry convergence has been achieved in 9 iterations 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 0.00052582 atom 3 type 1 force = 0.00000000 0.00000000 -0.00108418 atom 4 type 2 force = 0.00000000 0.00000000 -0.00111021 atom 5 type 1 force = 0.00000000 0.00000000 -0.00066898 atom 6 type 2 force = 0.00000000 0.00000000 0.00030722 atom 7 type 1 force = 0.00000000 0.00000000 -0.00150570 atom 8 type 2 force = 0.00000000 0.00000000 -0.00163780 atom 9 type 1 force = 0.00000000 0.00000000 0.00177984 atom 10 type 2 force = 0.00000000 0.00000000 0.00000000 atom 11 type 1 force = 0.00000000 0.00000000 -0.00177984 atom 12 type 2 force = 0.00000000 0.00000000 0.00163780 atom 13 type 1 force = 0.00000000 0.00000000 0.00150570 atom 14 type 2 force = 0.00000000 0.00000000 -0.00030722 atom 15 type 1 force = 0.00000000 0.00000000 0.00066898 atom 16 type 2 force = 0.00000000 0.00000000 0.00111021 atom 17 type 1 force = 0.00000000 0.00000000 0.00108418 atom 18 type 2 force = 0.00000000 0.00000000 -0.00052582 Total force = 0.004763 Total SCF correction = 0.002516 entering subroutine stress ... total stress (Ry/bohr**3) (kbar) P= 5650.32 0.02322957 0.00000000 0.00000000 3417.19 0.00 0.00 0.00000000 0.02322957 0.00000000 0.00 3417.19 0.00 0.00000000 0.00000000 0.06877108 0.00 0.00 10116.57 Wentzcovitch Damped Cell-Dynamics Minimization convergence thresholds: EPSE = 0.10E-04 EPSF = 0.10E-04 EPSP = 0.50E+00 Entering Dynamics; it = 1 time = 0.00000 pico-seconds ********************************************************************* The simulation goes through 23 complete Self-consistent Calculations. Here is the last self-consistent run (before the 24th run timed out): ********************************************************************* ! total energy = -216.83428802 Ry Harris-Foulkes estimate = -216.83428838 Ry estimated scf accuracy < 0.00000036 Ry convergence has been achieved in 10 iterations 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 -0.00120296 atom 3 type 1 force = 0.00000000 0.00000000 -0.00028879 atom 4 type 2 force = 0.00000000 0.00000000 0.00057200 atom 5 type 1 force = 0.00000000 0.00000000 0.00115400 atom 6 type 2 force = 0.00000000 0.00000000 -0.00030438 atom 7 type 1 force = 0.00000000 0.00000000 -0.00064802 atom 8 type 2 force = 0.00000000 0.00000000 -0.00012442 atom 9 type 1 force = 0.00000000 0.00000000 0.00095840 atom 10 type 2 force = 0.00000000 0.00000000 0.00000000 atom 11 type 1 force = 0.00000000 0.00000000 -0.00095840 atom 12 type 2 force = 0.00000000 0.00000000 0.00012442 atom 13 type 1 force = 0.00000000 0.00000000 0.00064802 atom 14 type 2 force = 0.00000000 0.00000000 0.00030438 atom 15 type 1 force = 0.00000000 0.00000000 -0.00115400 atom 16 type 2 force = 0.00000000 0.00000000 -0.00057200 atom 17 type 1 force = 0.00000000 0.00000000 0.00028879 atom 18 type 2 force = 0.00000000 0.00000000 0.00120296 Total force = 0.003045 Total SCF correction = 0.001829 entering subroutine stress ... total stress (Ry/bohr**3) (kbar) P= 1021.47 0.00437252 0.00000000 0.00000000 643.22 0.00 0.00 0.00000000 0.00437252 0.00000000 0.00 643.22 0.00 0.00000000 0.00000000 0.01208629 0.00 0.00 1777.95 Entering Dynamics; it = 24 time = 0.02226 pico-seconds ********************************************************************* It appears that my force(s) are not consistent with the force threshold that I set. I'm guessing this is because my initial guess at the structure is quite far from the relaxed structure. So, would it be reasonable to take the unit cell coordinates from the last completed self-consistent calcualtion and use those as starting coordinates for a brand new vc-relax run? This would be an effort to continue the calculation, but not lose the 3:30 of run time I've already used. Also, how would I handle a restart in this situation? Forgive me if this question is too basic. Thanks for the help Jason Larkin, PhD Student Carnegie Mellon University