[Pw_forum] Wrong effective charges in AFM insulator using "zue"
Andrea Dal Corso
dalcorso at sissa.it
Wed Jan 19 09:41:54 CET 2011
On Wed, 2011-01-19 at 16:27 +0800, xirainbow wrote:
> In 4.2.1 manual, it is said that:If .zue=true.is an alternative
> algorithm, different from the default one (if trans .and. epsil ) The
> results should be the same within numerical noise.
>
>
> However, I get wrong "effective charges" in zue=true in AFM insulator
> CaMnO3 with 4.2.1
> These two Mn atoms are the same except antiparallel spin.
> In "epsil+trans", effective charges of Mn1=7.79, Mn2=7.78;
> In "zue" , effective charges of Mn1=3.1, Mn2=51.2;
>
>
> I will describe my calculation procedure using 4.2.1 in short.
> 1: I do scf calculation in scf.in
> restart_mode = 'from_scratch'
> occupations = 'smearing'
> smearing = 'gauss'
> degauss = 0.002
> starting_magnetization(1) = 1
> starting_magnetization(2) = -1
> starting_magnetization(3) = 0
> starting_magnetization(4) = 0
>
>
> 2: I do a scf calculation in scf.in
> restart_mode = 'restart'
> occupations = 'fixed'
> nspin = 2
> tot_magnetization = 0
>
>
> 3: I do ph calculation with
> zue = .TRUE. !the same with epsil and trans = TRUE
> (In this condition, effective charges of Mn1=3.1, Mn2=51.2;)
> or with:
> epsil = .TRUE. , trans = .TRUE.
> (In this condition , effective charges of Mn1=7.79, Mn2=7.78;)
>
>
> (The reason is why I restart scf is below:
> "starting_magnetization" must be used with "smearing". However,
> "smearing" will give a metal result. Effective charges can not be
> calculated for metal. But, CaMnO3 is really a insulator AFM.
> "occupations=fixed" can get a insulator result. However it must used
> with "tot_magnetization". If I use "tot_magnetization=0", I will get a
> PM no AFM state.
> In the end, I use "smearing"+"starting_magnetization" to get a AFM
> metal. Then I use "fixed"+"tot_magnetization" to get a AFM insulator.
> Is there any other good method to get a AFM insulator?)
>
>
>
> The following my script for "zue= .TRUE "
> And I have attached output file of "zue= .TRUE " in accessary.
> Thanks:)
The phonon with LSDA + constraint is not programmed. So it will not
work. If the AFM insulator is the ground state then you should obtain it
with noncolin=.true. without constraint. In this case ph.x at gamma
should work and you should get the correct effective charges. If not
please provide the complete input.
HTH,
Andrea
>
> #*********************************************
> # scf-antimag-smearing
> cat>scf.in<<EOF
> for vc-relax
> &CONTROL
> calculation = 'scf'
> title = 'G-10-scf'
> verbosity = 'high'
> restart_mode = 'from_scratch'
> wf_collect = .FALSE.
> tstress = .TRUE.
> tprnfor = .TRUE.
> prefix = 'G-10-scf'
> etot_conv_thr = 1.0e-4
> forc_conv_thr = 1.0e-3
> disk_io = 'low'
> pseudo_dir = './'
> /
>
>
> &SYSTEM
> ibrav = 2
> celldm = 14.20419765
> nat = 10
> ntyp = 4
> nbnd = 50
> ecutwfc = 70
> ecutrho = 560
> nosym = .FALSE.
> !nosym_evc = .TRUE.
> !noinv = .TRUE.
> occupations = 'smearing'
> smearing = 'gauss'
> degauss = 0.002
> starting_magnetization(1) = 1
> starting_magnetization(2) = -1
> starting_magnetization(3) = 0
> starting_magnetization(4) = 0
> !occupations = 'fixed'
> nspin = 2
> !tot_magnetization = 0
> /
>
>
> &ELECTRONS
> electron_maxstep = 100
> conv_thr = 1.0e-7
> mixing_mode = 'plain'
> mixing_beta = 0.7
> mixing_ndim = 8
> diagonalization = 'david'
> diago_david_ndim = 4
> /
>
>
> ATOMIC_SPECIES
> Mn1 55 Mn.pbe-sp-van.UPF
> Mn2 55 Mn.pbe-sp-van.UPF
> Ca 40 Ca.pbe-nsp-van.UPF
> O 16 O.pbe-rrkjus.UPF
>
>
> ATOMIC_POSITIONS {crystal}
> Mn1 0.00 0.00 0.00
> Mn2 0.50 0.50 0.50
> Ca 0.25 0.25 0.25
> Ca 0.75 0.75 0.75
> O 0.75 0.25 0.75
> O 0.25 0.75 0.25
> O 0.75 0.75 0.25
> O 0.25 0.25 0.75
> O 0.25 0.75 0.75
> O 0.75 0.25 0.25
>
>
>
> K_POINTS {automatic}
> 6 6 6 0 0 0
> EOF
> ./dopw <scf.in >G-scf-10-smearing.out
>
>
> # scf-antimag-insulator
> cat>scf.in<<EOF
> for vc-relax
> &CONTROL
> calculation = 'scf'
> title = 'G-10-scf'
> verbosity = 'high'
> restart_mode = 'restart'
> wf_collect = .FALSE.
> tstress = .TRUE.
> tprnfor = .TRUE.
> prefix = 'G-10-scf'
> etot_conv_thr = 1.0e-4
> forc_conv_thr = 1.0e-3
> disk_io = 'low'
> pseudo_dir = './'
> /
>
>
> &SYSTEM
> ibrav = 2
> celldm = ${lattic_parameter} !bohr
> nat = 10
> ntyp = 4
> nbnd = 50
> ecutwfc = 70
> ecutrho = 560
> nosym = .FALSE.
> !nosym_evc = .TRUE.
> !noinv = .TRUE.
> !occupations = 'smearing'
> !smearing = 'gauss'
> !degauss = 0.002
> !starting_magnetization(1) = 1
> !starting_magnetization(2) = -1
> !starting_magnetization(3) = 0
> !starting_magnetization(4) = 0
> occupations = 'fixed'
> nspin = 2
> tot_magnetization = 0
> /
>
>
> &ELECTRONS
> electron_maxstep = 100
> conv_thr = 1.0e-7
> mixing_mode = 'plain'
> mixing_beta = 0.7
> mixing_ndim = 8
> diagonalization = 'david'
> diago_david_ndim = 4
> /
>
>
> ATOMIC_SPECIES
> Mn1 55 Mn.pbe-sp-van.UPF
> Mn2 55 Mn.pbe-sp-van.UPF
> Ca 40 Ca.pbe-nsp-van.UPF
> O 16 O.pbe-rrkjus.UPF
>
>
> ATOMIC_POSITIONS {crystal}
> Mn1 0.00 0.00 0.00
> Mn2 0.50 0.50 0.50
> Ca 0.25 0.25 0.25
> Ca 0.75 0.75 0.75
> O 0.75 0.25 0.75
> O 0.25 0.75 0.25
> O 0.75 0.75 0.25
> O 0.25 0.25 0.75
> O 0.25 0.75 0.75
> O 0.75 0.25 0.25
>
>
>
> K_POINTS {automatic}
> 6 6 6 0 0 0
> EOF
> ./dopw <scf.in >G-scf-10-insulator.out
>
>
> #for phonon-antimag
> cat>ph.in <<EOF
> for phonon
> &INPUTPH
> amass(1) = 55
> amass(2) = 55
> amass(3) = 40
> amass(4) = 16
> outdir = "./"
> prefix = 'G-10-scf' !must be the same with scf
> ldisp = .FALSE.
> niter_ph = 100
> tr2_ph = 1.0e-12
> alpha_mix(1)= 0.7
> nmix_ph = 4
> iverbosity = 1
> fildyn = 'matdyn'
> !epsil = .TRUE. !Do not set epsil to .true. for metallic system
> or q/=0
> !trans = .TRUE. !if trans .and. epsil effective charges are
> calculated
> zue = .TRUE. !the same with epsil and trans = TRUE
> /
> 0.0 0.0 0.0
> EOF
>
>
> ./doph <ph.in >G-ph-10.out
> done
> #*********************************************
>
> --
> ____________________________________
> Hui Wang
> School of physics, Fudan University, Shanghai, China
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--
Andrea Dal Corso Tel. 0039-040-3787428
SISSA, Via Bonomea 265 Fax. 0039-040-3787249
I-34136 Trieste (Italy) e-mail: dalcorso at sissa.it
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