Comment 8 for bug 1834949

Dear Mr. Papior,

it is still a bit strange:
In both calculations with the mixing modifications, but one with the modified code, dH still jumps

--- Without Code Modification ----
   scf: 8 -1804868.778352 -1804868.732982 -1804868.733022 0.001146 -2.812871 0.312873
   scf: 9 -1804868.749710 -1804868.735597 -1804868.735641 0.000361 -2.813709 0.234864
Geom step, scf iteration, dmax: 0 10 0.017262
redata: Recompute H after scf cycle = F
siesta: DUscf = 413.344772
        iscf Eharris(eV) E_KS(eV) FreeEng(eV) dDmax Ef(eV) dHmax(eV)
   scf: 1 -1804421.557777 -1804719.910852 -1804719.911018 0.050963 -2.853464 62.730089
   scf: 2689464237.365204228548699.015671228548699.015350 51.191287-18.050496**********
   scf: 3 -1807335.880661 -1804834.918607 -1804834.918839 51.191233 -2.792301 28.033179
   scf: 4 -1804850.731953 -1804845.865303 -1804845.865456 0.010372 -2.813543 24.742072

--- With Code Modification ----
   scf: 8 -1804868.778352 -1804868.732982 -1804868.733022 0.001146 -2.812871 0.312873
   scf: 9 -1804868.749710 -1804868.735597 -1804868.735641 0.000361 -2.813709 0.234864
Geom step, scf iteration, dmax: 0 10 0.017262
redata: Recompute H after scf cycle = F
siesta: DUscf = 413.344772
        iscf Eharris(eV) E_KS(eV) FreeEng(eV) dDmax Ef(eV) dHmax(eV)
   scf: 1 -1804421.557777 -1804719.910852 -1804719.911018 0.050963 -2.853464 62.730089
   scf: 2 -1804742.932702 -1804731.529616 -1804731.529750 0.002985 -2.849860 60.125657
   scf: 3 -1804889.097349 -1804864.557415 -1804864.557459 0.043795 -2.827967 11.121388
   scf: 4 -1804867.632473 -1804866.689589 -1804866.689632 0.003100 -2.820711 8.032126

interestingly, the 2nd Jump is less severe and thereafter it converges quickly. So that modification is clearly useful. But the problem is still there.
Concerning the mixing, Siesta prints:

ps356562: cat GST.out | grep mixing
mix.SCF: Pulay mixing = Pulay
mix.SCF: Linear mixing weight = 0.020000
mix.SCF: Pulay mixing = Pulay
mix.SCF: Linear mixing weight = 0.020000
mix.SCF: Spin-component mixing all
mix.SCF: Pulay mixing = Pulay
mix.SCF: Linear mixing weight = 0.000100
mix.SCF: Spin-component mixing all

the last step is the restarted (soc from soc) one. Apparently it applies the linear mixing correctly.

BUT:
I also tried with permanent Linear mixing, and setting both the initial mixing weight and the later mixing weight to zero.
However, this did not circumvent the initial dH jump (although, with the code modification, the 2nd dDmax jump to 51.* would probably not have happened)

        iscf Eharris(eV) E_KS(eV) FreeEng(eV) dDmax Ef(eV) dHmax(eV)
   scf: 1 -1804421.557777 -1804719.910852 -1804719.911018 0.050963 -2.853464 62.730089
   scf: 2689464237.365204228548699.015671228548699.015350 51.191287-18.050496**********
   scf: 3228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 4228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 5228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 6228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 7228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 8228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
   scf: 9228548699.015671228548699.015671228548699.015350 0.000000-18.050496**********
Geom step, scf iteration, dmax: 0 10 5826.262685

Interestingly, the dDmax, Efermi and possibly dH does not change anymore after the initial 2 jumps, as it is supposed to be for zero mixing weight.
But since the initial jumps are still there, i would guess that the problem either lies in the very initialization / reloading of the density matrix / Hamiltonian, or that the first mixing is not performed as intended.

Is it possible to load H directly ?