[QE-users] Convergence problem in vc-relax

Lorenzo Bastonero lbastone at uni-bremen.de
Tue Jul 12 17:49:50 CEST 2022


Hi,

At first look it seems your cutoff is a bit too small, as well as your conv_thr.
Pressure usually is rather affected by low cutoff. I’d expect at least 80/90 Ry cutoff for converged results within sensible parameters.

Best,
Lorenzo

Inviato da iPhone

> Il giorno 12 lug 2022, alle ore 17:40, Ali Jaberi <ali.jaberi at mail.mcgill.ca> ha scritto:
> 
> 
> Hi,
> 
> I am trying to relax the structure for Li(Ni1/3Mn1/3Co1/3)O2. I could relax the structure with VASP but not with Quantum ESPRESSO. I have tried changing so many parameters but could not get any result so end up posting my problem here.
> 
> Here is my input file:
> 
> -----------------------------------------------------------------------------------------
> &control
>     calculation='vc-relax'
>     nstep = 500,
>     restart_mode = 'from_scratch' ,
>     pseudo_dir = '....' ,
>     outdir = './outdir'
>     prefix = 'NMC',
>     verbosity ='high' ,
>     tprnfor = .true.
>     etot_conv_thr= 1.0D-3
>     forc_conv_thr = 1.0D-2
> /
> 
> &system
>     ibrav = 0,
>     nat =36,
>     ntyp =5,
>     ecutwfc = 34 ,
>     ecutrho = 380,
>     occupations ='smearing',
>     smearing='mv',
>     degauss=0.001,
>     nspin = 2,
>     starting_magnetization(2)=0.7,
>     starting_magnetization(3)=0.7,
>     starting_magnetization(4)=0.7,
>     lda_plus_u = .true.
>     Hubbard_U(2)=4.84,
>     Hubbard_U(3)=5.0,
>     Hubbard_U(4)=5.96,
> /
> 
> &electrons
>     electron_maxstep = 700
>     conv_thr = 1.0d-4,
>     mixing_beta = 0.3,
>     diagonalization = 'david',
> /
> 
> &IONS
>     ion_dynamics      = "bfgs",
> /
> 
> &CELL
>    cell_dynamics = 'bfgs'
>    press_conv_thr = 0.9
> /
> 
> ATOMIC_SPECIES
> Li   6.940  Li.pbe-sl-rrkjus_psl.1.0.0.UPF
> Mn  54.938  Mn.pbe-spn-rrkjus_psl.0.3.1.UPF
> Co  58.933  Co.pbe-spn-rrkjus_psl.0.3.1.UPF
> Ni  58.693  Ni.pbe-spn-rrkjus_psl.1.0.0.UPF
> O   15.999  O.pbe-n-rrkjus_psl.1.0.0.UPF
> 
> CELL_PARAMETERS angstrom
> 4.92404724        0.00000000        0.00000000
> -2.46202362        4.26435000        0.00000000
> 0.00000000        0.00000000       14.14560000
> 
> ATOMIC_POSITIONS angstrom
> Co       -0.81985389        4.26292856       11.78328480
> Co        0.82231591        1.42144999        2.34816960
> Co        2.46202362        4.26435000        7.07280000
> Li        0.00000000        0.00000000        0.00000000
> Li       -0.81985389        4.26292856        4.71048480
> Li        0.82231591        1.42144999        9.42096960
> Li       -0.00000003        2.84290001        0.00000000
> Li        1.64216978        2.84147854        4.71048480
> Li        3.28433951        0.00000000        9.42096960
> Li        2.46202364        1.42144999        0.00000000
> Li       -0.81985387        1.42002855        4.71048480
> Li       -1.63970776        2.84290001        9.42096960
> Mn       -0.00000003        2.84290001        7.07280000
> Mn        1.64216978        2.84147854       11.78328480
> Mn        3.28433951        0.00000000        2.34816960
> Ni        2.46202364        1.42144999        7.07280000
> Ni       -0.81985387        1.42002855       11.78328480
> Ni       -1.63970776        2.84290001        2.34816960
> O         0.00000000        0.00000000        3.38910187
> O         0.00000000        0.00000000       10.75649813
> O        -0.81985389        4.26292856        8.09958667
> O        -0.81985389        4.26292856        1.32138293
> O         0.82231591        1.42144999       12.81007147
> O         0.82231591        1.42144999        6.03186773
> O        -0.00000003        2.84290001        3.38910187
> O        -0.00000003        2.84290001       10.75649813
> O         1.64216978        2.84147854        8.09958667
> O         1.64216978        2.84147854        1.32138293
> O         3.28433951        0.00000000       12.81007147
> O         3.28433951        0.00000000        6.03186773
> O         2.46202364        1.42144999        3.38910187
> O         2.46202364        1.42144999       10.75649813
> O        -0.81985387        1.42002855        8.09958667
> O        -0.81985387        1.42002855        1.32138293
> O        -1.63970776        2.84290001       12.81007147
> O        -1.63970776        2.84290001        6.03186773
> 
> K_POINTS automatic
> 4 4 4 0 0 0
> -----------------------------------------------------------------------------------------
> 
> Ther pressures I got for this relaxation are very high at each step!!!
> 
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -23972.31
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -26659.21
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24871.74
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24165.07
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24040.51
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -23928.12
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -23974.47
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24023.37
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24016.41
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24102.96
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24097.08
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24080.78
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -26559.80
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24814.82
>           total   stress  (Ry/bohr**3)                   (kbar)     P=   -24024.82
> 
> This is exactly the structure VASP could converge so there should be a problem in the parameters or the algorithm. I really appreciate it if anyone could help me with this.
> 
> Best.
> Ali Jaberi
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