hello I'm having convergence problems with a turbo-davidson calculation on an isolated (neutral) molecule of a Ru complex:
http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/XEDFAQ_1.png I have limited experience with this kind of calcs, but some time ago I did similar calcs on another molecule of the same type without any apparent problem (see also below). So far my protocol is: => geometry relaxation of the isolated molecule (cubic cell (a=21.50 ang) with a minimum inter-image distance of 10.1 ang, gamma point) => scf calculation with nbnd=120 (there are 96 occupied bands) http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/scf.in.txt => turbo-davidson run: http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/davidson.in.txt ----8<---- &lr_input outdir='./tmp', restart=.false. / &lr_dav p_nbnd_occ=10 p_nbnd_virt=10 num_init=60 num_eign=25 num_basis_max=200 residue_conv_thr=1.0E-4 start=0.18866813 ! 483 nm finish=0.23792873 ! 383 nm step=0.001 reference=0.21021155 ! 433.5 nm broadening=0.005 poor_of_ram=.true. poor_of_ram2=.true. lplot_drho=.true. / ----8<---- As said, the turbo-davidson calculation doesn't seem to be going anywhere; here is a typical pattern of the "Largest residue" figure vs n. of iterations: http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/convergence.png and here is an output: http://www.dsch.univ.trieste.it/~balducci/tmp/turbo-davidson-problem/davidson.out.txt Things that I have tried (with no joy, and, I must admit, without knowing very well what I was doing): => increase num_init => decrease num_eign => decrease the energy range (start,finish) => increase num_basis_max => switch vdW-DF off in the scf run => increase p_nbnd_occ and p_nbnd_virt The only way I could get a converged result so far has been to request a single eigenvalue (num_eign=1): however, I guess this is simply extreme tweaking of the calculation: even in this conditions, it took some 22 iterations to converge, which seems too much to me. I have tried to reproduce my previous calc (the one which worked smoothly) since qe version at the time was different (I'm presently using qe-6.5); the molecule was this (ionic species, charge +2): http://www.dscf.units.it/~balducci/tmp/turbo-davidson-problem/fbt1805_1.png With the following input: ----8<---- &lr_input outdir='./tmp', restart=.false. / &lr_dav p_nbnd_occ=10 p_nbnd_virt=10 num_init=60 num_eign=25 num_basis_max=200 residue_conv_thr=1.0E-4 start=0.15 finish=0.185 step=0.001 broadening=0.005 reference=0.1675 poor_of_ram=.true. poor_of_ram2=.true. lplot_drho=.true. / ---->8---- the calculation converges straightforwardly with qe-6.5: ----8<---- Largest residue: 0.051299398950 Largest residue: 0.014049254805 Largest residue: 0.005898374852 Largest residue: 0.002998212328 Largest residue: 0.003119825980 Largest residue: 0.001028311667 Largest residue: 0.000741910032 Largest residue: 0.000399386757 Largest residue: 0.000545167736 Largest residue: 0.000146498010 Largest residue: 0.000098106072 ---->8---- I'm out of ideas and hoping that someone on the list can give me a clue (apologies: I realize that the statement of the problem is rather vague, but I don't know how to be more precise than this) Needless to say, I will be happy to provide any further information which might be useful thanks a lot in advance for any hint/suggestion ciao -gabriele -- Gabriele Balducci - Dipartimento di Scienze Chimiche e Farmaceutiche - Via L. Giorgieri 1 I-34127 TRIESTE tel: I-040-5583957 fax: I-040-5583903 e-mail: [email protected] Please, if possible, don't send me MS Word or PowerPoint attachments Why? See: http://www.gnu.org/philosophy/no-word-attachments.html _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
