[QE-users] BEEF-vdW, RISM and nspin = 2: large energy fluctuations

[Paolo Giannozzi]

Maybe the following note in file Doc/release-notes is relevant for your
problem?
---
...
Fixed in 6.8 version:
...
   * The rho => 0 limit of spin-polarized BEEF XC energy was not correct,
    leading to funny total energy numbers and problems in structural
optimization
    (fixed by Gabriel S. Gusmão, Georgia Tech)
---

Paolo

On Thu, Nov 18, 2021 at 3:06 PM Tom Demeyere <T.Demeyere at soton.ac.uk> wrote:

> Dear users,
>
> I am trying to calculate binding energies using the BEEF-vdW and the RISM
> formalism (QE-6.7), for this aim I need to compute different molecules
> (H2O, O2, …) in H2O with HCl 1M.
>
> O2 shows large energy fluctuations when I ask for:
>
> - input_dft: “BEEF-vdW”
> - nspin = 2
>
> (The calculation converges when asking for nspin = 0, or changing the
> functional to PBE.)
>
> Typical output:
>
> …
>
> iteration #  8
> ...
>      total energy              =    -180.99829260 Ry
>      estimated scf accuracy    <       0.00029814 Ry
> …
> iteration #  9
> ...
>      total energy              =    -151.60027495 Ry
>      estimated scf accuracy    <       0.00021978 Ry
> …
> iteration # 10
>      total energy              =    -139.03397732 Ry
>      estimated scf accuracy    <       0.00010331 Ry
> …
>
> The calculation ends at some point with: “history already reset at
> previous step: stopping”, the final energy given is wrong.
>
> Full input:
>
> &CONTROL
>   calculation = 'relax'
>   etot_conv_thr = 1.0000000000d-05
>   forc_conv_thr = 5.0000000000d-04
>   pseudo_dir = '/work/e89/e89/td5g20/PseudoPotentials/'
>   tprnfor = .true.
>   verbosity = 'high'
>   trism = .true.
> /
> &SYSTEM
>   ecutwfc = 60, ecutrho = 480
>   occupations = ‘smearing’, smearing = ‘fd’, degauss = 0.01
>   ibrav = 1, A = 20
>   ntyp = 1, nat = 2
>   nosym = .true.
>   input_dft = "BEEF-vdW"
> /
> &ELECTRONS
>   conv_thr = 1.00D-12
>   mixing_mode = ‘local-TF’,  mixing_beta = 0.2
> /
> &IONS
>   ion_dynamics = "bfgs"
> /
> &RISM
>   nsolv = 3
>   closure = 'kh'
>   tempv = 298.15
>   ecutsolv = 160.0
>   starting1d = 'zero'
>   rism1d_conv_thr = 1.0e-8
>   rism1d_maxstep = 100000
>   mdiis1d_size = 20
>   mdiis1d_step = 0.1
>   starting3d = 'zero'
>   rism3d_maxstep = 10000
>   rism3d_conv_thr = 1.0e-6
>   rism3d_conv_level = 0.5
>   mdiis3d_size = 20
>   mdiis3d_step = 0.8
>   solute_lj(1) = 'none'
>   solute_epsilon(1) = 0.1554
>   solute_sigma(1) = 3.1660
> /
> ATOMIC_SPECIES
> O   15.999 O.pbe-n-kjpaw_psl.1.0.0.UPF
> ATOMIC_POSITIONS angstrom
> O             1.6891044673        1.7570200245        0.6442147904
> O             2.3377455327        0.7138399755        0.6439152096
> K_POINTS gamma
> SOLVENTS mol/L
> H2O  -1.0  H2O.spc.MOL
> H3O+  1.0  H3O+.aq.MOL
> Cl-   1.0  Cl-.aq.MOL
>
> Best regards,
> Tom Demeyere
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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