[Wien] Force convergence within SCF cycle

[Stefaan Cottenier]

Everything fine. When you use '-I -fc 1.0', only in the *last* iteration 
'TOT' is changed to 'FOR' in case.in2 (to include Pulay corrections), 
and this is the big jump you see. The three preceding iterations are 
constant within 1.0, in agreement with your convergence criterium. If 
you would remove the -I and put FOR manually right from the start, you 
would see the number converging to 81 directly, but it would take an 
unnecessary amount of extra computer time in lapw2.

Stefaan

>Dear WIEN2k users,
>
>would you please comment on convergence of forces during the SCF-run. I
>perform the energy minimization with respect to atomic positions for
>GaAs:N [64-atom zinc-blend supercell with one As atom replaced by N
>(nitrogen)]. After the first SCF cycle I have:
>
>~> grep :FOR002 *scf
>GaAsN64_1.scf::FOR002:   2.ATOM        129.498          0.000          0.000        129.498
>GaAsN64_1.scf::FOR002:   2.ATOM        162.260          0.000          0.000        162.260
>GaAsN64_1.scf::FOR002:   2.ATOM         60.859          0.000          0.000         60.859
>GaAsN64_1.scf::FOR002:   2.ATOM         36.923          0.000          0.000         36.923
>GaAsN64_1.scf::FOR002:   2.ATOM         19.557          0.000          0.000        -19.557
>GaAsN64_1.scf::FOR002:   2.ATOM         37.737          0.000          0.000         37.737
>GaAsN64_1.scf::FOR002:   2.ATOM         27.782          0.000          0.000        -27.782
>GaAsN64_1.scf::FOR002:   2.ATOM          3.583          0.000          0.000         -3.583
>GaAsN64_1.scf::FOR002:   2.ATOM          2.685          0.000          0.000         -2.685
>GaAsN64_1.scf::FOR002:   2.ATOM          3.882          0.000          0.000          3.882
>GaAsN64_1.scf::FOR002:   2.ATOM          6.754          0.000          0.000          6.754
>GaAsN64_1.scf::FOR002:   2.ATOM          7.020          0.000          0.000          7.020
>GaAsN64_1.scf::FOR002:   2.ATOM          7.479          0.000          0.000          7.479
>GaAsN64_1.scf::FOR002:   2.ATOM         81.647          0.000          0.000         81.647
>
>QUESTION: Do forces converge within the SCF-cycle? The last step
>(transition from 7.479 to 81.647) looks suspicious. How does it correspond
>to the -fc 1.0 option?
>
>ADDITIONAL INFORMATION: Run command ~>min -i 100 -s 10 -j 'run_lapw -I -i
>40 -fc 1.0 '; method PORT; LDA; Spin polarization - NO; Rmt(Ga)=1.92;
>Rmt(As)=2.0;  Rmt(N)=1.75; Kmax*Rmt_min = 7; 1 k-point (shifted) (2x2x2);
>Lmax = 12 (in *in1c); for the rest I use default values. Such parameters
>produce reliable results for binaries (GaAs and GaN) and ensure absence of
>ghost-states.
>
>Thank you in advance,
>Oleg Rubel
>
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