On Wed, Sep 7, 2011 at 3:28 PM, Elie Moujaes <elie.moujaes at hotmail.co.uk> wrote: > Dear all, >
Dear Elie, > > I am relaxing a 60 atom supercell (graphene grain boundary) to make the > total force on atoms mainly 0.001 Ry/au. However the vc-relax stopped after > 4 days of execution and without reaching the desired force threshold. The > following output was obtained : > > Please can anyone advice me on this? Shall I start with the new > configuration and start relaxing again? > I'm also doing some cell relaxation. As I understand, cell optimization is not very easy, and it is common that it does not converge after a very long run. Surely you should restart the calculation to achieve your convergence criteria. You can just change the "restart_mod = 'from_scratch' " to "restart_mode = 'restart' ", and submit the job again to continue from where you stopped. Please be advised that pw.x will read cell parameters / atomic positions, initial density, pseudopotentials from the folder of GBphonon.save, so make sure you copy the folder to computing-nodes. However, I highly suggest you do something to accelerate the convergence. For example, if you do not expect the cell angle to change (i.e. keep angles=90), you may add the following keywords to the &CELL section. cell_dofree = xyz This will greatly reduce the uncertainty of the geometry optimization. and reduce energy/force oscillation. Another great idea is to manually choose x, y and z, then do a relaxation of atomic positions only. and plot the total energy changes with x, y and z. However, be noted that different volume means different numbers of PW basis function, and energy comparison in this way could be a little confusing. Anyway, if volume change is not large, still this would help a lot. Since I'm also a learner, any more comments or correction to my comments are welcome. Thanks Xijun > > Regards > > > > Elie Moujaes > > University of Nott > > University Park > > NGT 3RD > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- Department of Chemistry and Biochemistry, Concordia University 7141 Sherbrooke Ouest, Montreal, QC H4B 1R6 Tel: 514-848-2424-#5835 (Lab) TA office: SP175.23
