Dear Giovanni, Thanks for the prompt response, I will do as you suggested. The above data was obtained without fixing ecutrho to480 (it was commented) . I felt that may be a lower kpoint grid or wrong smearing might be the source. I will do as you suggested and get back to you. Thanks again. Adwait Ph.D. Student, Gujarat University, Gujarat, India. On 23-Oct-2015 8:56 pm, "Giovanni Cantele" <[email protected]> wrote:
> one of the problems that you might be running across is that you keep > ecutrho fixed. That means that with ecutwfc=30, ecutrho/ecutwfc=16, whereas > with ecutwfc=120, the same ratio is 4. The latter is definitely too small > for ultrasoft pseudo potentials, that you are including in your > calculation. In other words, you might be comparing values of the total > energies with different convergence levels with respect to ecutrho, which > can be the origin (or a partial explanation) of the oscillations you find. > > I would try (maybe this will not solve your problem!) to retry the test as > a function of ecutwfc, as you did, but keeping the ecutrho/ecutwfc ratio > (rather than the ecutrho variable) constant, to a more or less safe value > (e.g. 8). > > Giovanni > > > On 23 Oct 2015, at 17:05, adwait mevada <[email protected]> wrote: > > > > Dear All, > > I am trying to find optimal ecutwfc for CaMg2. > > As a first step i varied ecutwfc from 30-150 but i found that > > energy was fluctuating > > I cannot decide what to set for ecutrho if my ecutwfc is fluctuating > > , what can be the reason for this? any help in this regard is > appreciated. > > > > note : i am not finding ecutwfc for equilibrium volume. > > > > I am attaching png output of gnuplot for it. > > > > data for various ecutwfc > > ecut energy vol kpoints stress time. > > 30 -932.78387473 1314.9516 40 459.00 7m 4.75s > > 40 -932.78292968 1314.9516 40 458.52 10m35.69s > > 50 -932.78368793 1314.9516 40 458.74 14m22.97s > > 60 -932.78388413 1314.9516 40 458.90 17m48.05s > > 70 -932.78547210 1314.9516 40 457.91 25m37.98s > > 80 -932.78563717 1314.9516 40 459.77 29m17.84s > > 90 -932.78419457 1314.9516 40 459.42 35m28.98s > > 100 -932.78387315 1314.9516 40 458.78 37m40.76s > > 110 -932.78425940 1314.9516 40 458.38 41m34.44s > > 120 -932.78459959 1314.9516 40 458.94 52m35.88s > > 130 -932.78422725 1314.9516 72 459.24 2h 0m > > 140 -932.78394222 1314.9516 72 458.91 2h 3m > > 150 -932.78396419 1314.9516 72 458.69 2h30m > > my input file is: > > C=9 > > A=5 > > for ECUT in 30 40 50 60 70 80 90 100 ; do > > cat > camg2e$ECUT.in << EOF > > &control > > calculation = 'scf' > > prefix='camg2e$ECUT', > > tstress = .true. > > tprnfor = .true. > > / > > &system > > ibrav=4, a=$A ,c=$C ,nat=12, ntyp=2, > > ecutwfc=$ECUT ! ,ecutrho=480, > > occupations='smearing',smearing="mv",degauss=0.02, > > / > > &electrons > > diagonalization='david' > > mixing_mode = 'plain' > > mixing_beta = 0.7 > > conv_thr = 1.0d-8 > > / > > ATOMIC_SPECIES > > Mg 24.305 Mg.pw91-np-van.UPF > > Ca 40.078 Ca.pw91-nsp-van.UPF > > ATOMIC_POSITIONS crystal > > Ca 0.3333333 0.6666667 0.0668052 > > Ca 0.3333333 0.6666667 0.4331948 > > Ca 0.6666667 0.3333333 0.5668053 > > Ca 0.6666667 0.3333333 0.9331947 > > Mg 0.0000000 0.0000000 0.0000000 > > Mg 0.0000000 0.0000000 0.5000000 > > Mg 0.3397683 0.1698842 0.2500000 > > Mg 0.8301158 0.6602317 0.2500000 > > Mg 0.1698842 0.8301158 0.7500000 > > Mg 0.8301158 0.1698842 0.2500000 > > Mg 0.1698842 0.3397683 0.7500000 > > Mg 0.6602317 0.8301158 0.7500000 > > K_POINTS automatic > > 8 8 4 1 1 1 > > EOF > > mpirun -np 4 pw.x -in camg2e$ECUT.in > camg2e$ECUT.out > > ENERGY=`grep ! camg2e$ECUT.out | cut -b 33-49` > > VOL=`grep volume camg2e$ECUT.out | cut -b 33-45 ` > > KP=`grep points= camg2e$ECUT.out | cut -b 25-31` > > TIME=`grep "PWSCF " camg2e$ECUT.out | cut -b 37-47` > > STRESS=`grep "total stress" camg2e$ECUT.out | cut -b 72-78` > > FOR=`grep "Total force " camg2e$ECUT.out` > > echo "$ECUT $ENERGY $ALAT $VOL $KP $STRESS $TIME $FOR" > > sleep 60 > > echo "$ECUT $ENERGY $ALAT $VOL $KP $STRESS $TIME $FOR" >> > camg2r480.dat > > done > > > > Thank you for your help in advance > > > > -- > > -Adwait > > Ph.D. Student, > > Gujarat University, > > Gujarat, India. > > <camg2ecut.png>_______________________________________________ > > Pw_forum mailing list > > [email protected] > > http://pwscf.org/mailman/listinfo/pw_forum > > -- > > Giovanni Cantele, PhD > CNR-SPIN > c/o Dipartimento di Fisica > Universita' di Napoli "Federico II" > Complesso Universitario M. S. Angelo - Ed. 6 > Via Cintia, I-80126, Napoli, Italy > e-mail: [email protected] > Phone: +39 081 676910 > Skype contact: giocan74 > > ResearcherID: http://www.researcherid.com/rid/A-1951-2009 > Web page: http://people.na.infn.it/~cantele > > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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