[Pw_forum] Total energy does not coverge with ecut
Timothy Mason
thmason24 at yahoo.com
Thu Nov 6 16:44:45 CET 2008
Gentlemen,
My structures do not see to be converging
with increased ecutwfc. I'm setting ecutrho to ecutwfc * 12 and using
US PP. below is a table of ecut values vs energies vs difference
from previous steps followed by my input file followed by part of the output
file. It appears to begin to converge and 120 ecut but then jumps at
130 and then more at 140. I understood that convergence should be
pretty well achieved by 30 ecut for US PP. The only thing I change
between runs are the two ecut parameters. Any ideas as to what I'm
doing wrong or what I should be expecting?
A follow up
question in that I'm trying to do vc-relax based on this scf and the
forces decrease until a value of about 0.0003 and then oscillate around
this value. could that be related to the ecut convergence problem
I'm having?
thanks,
Tim Mason, University of Missouri St. Louis Department of Physics and astronomy
------------------------------------------------------------------------------------
ecutwfc total energy difference from previous
100 -48.21607621
105 -48.21651331 0.0004371
110 -48.21672787 0.00021456
120 -48.21686396 0.00013609
130 -48.2172448 0.00038084
140 -48.21819748 0.00095268
----------------------------------------------------------------------
&CONTROL
calculation = "scf",
prefix = 'n4_scf.out',
tprnfor = .TRUE.
pseudo_dir = '/home/thmmqc/pwscf/psps/US_GGA',
outdir='/home/thmmqc/tmp'
etot_conv_thr = 1.d-8
/
&SYSTEM
ibrav =
0, nat = 8, ntyp = 3,
ecutwfc = 100
ecutrho = 1200
celldm(1) = 1.889725989
/
&ELECTRONS
diagonalization = 'cg',
mixing_mode = 'plain',
mixing_beta = 0.7,
conv_thr = 1.0D-8
/
ATOMIC_SPECIES
Li 6.941000 Li.pbe-n-van.UPF
N 14.006740 N.pbe-van_ak.UPF
H 1.007940 H.pbe-van_ak.UPF
CELL_PARAMETERS
10.52658029 -1.08441956 -0.28831668
-2.96581684 6.61198966 -0.14661465
1.15738394 0.29429438 3.51384172
ATOMIC_POSITIONS {crystal}
Li 0.403906747000 0.720101910000 0.473406799000
Li 0.228004145000 0.310445951000 0.053578743000
N 0.230067712000 0.303154666000 0.552891390000
N 0.403264134000 0.730145360000 -0.024840278000
H 0.185705821000 0.137557379000 0.553855070000
H 0.132830606000 0.318409519000 0.624406047000
H 0.486061391000 0.685122024000 -0.095482152000
H 0.467101514000 0.897467040000 -0.051109646000
K_POINTS automatic
2 2 2 0 0 0
---------------------------------------------------------------------------------------------------------------------
Program PWSCF v.4.0.2 starts ...
Today is 6Nov2008 at 8:30: 1
Parallel version (MPI)
Number of processors in use: 1
For Norm-Conserving or Ultrasoft (Vanderbilt) Pseudopotentials or PAW
Current dimensions of program pwscf are:
Max number of different atomic species (ntypx) = 10
Max number of k-points (npk) = 40000
Max angular momentum in pseudopotentials (lmaxx) = 3
Iterative solution of the
eigenvalue problem
Too few procs for parallel algorithm
we need at least 4 procs per pool
a serial algorithm will be used
Planes per process (thick) : nr3 = 96 npp = 96 ncplane =51840
Planes per process (smooth): nr3s= 54 npps= 54 ncplanes=17280
Proc/ planes cols G planes cols G columns G
Pool (dense grid) (smooth grid) (wavefct grid)
1 96 32843 1954809 54 10579 357021 2893
51177
bravais-lattice index = 0
lattice parameter (a_0) = 1.8897 a.u.
unit-cell volume = 1595.0644 (a.u.)^3
number of atoms/cell = 8
number of atomic types = 3
number of electrons = 16.00
number of Kohn-Sham
states= 8
kinetic-energy cutoff = 140.0000 Ry
charge density cutoff = 1740.0000 Ry
convergence threshold = 1.0E-08
mixing beta = 0.7000
number of iterations used = 8 plain mixing
Exchange-correlation = SLA PW PBE PBE (1434)
celldm(1)= 1.889726
celldm(2)= 0.000000 celldm(3)= 0.000000
celldm(4)= 0.000000 celldm(5)= 0.000000 celldm(6)= 0.000000
crystal axes: (cart. coord. in units of a_0)
a(1) = ( 10.526580 -1.084420 -0.288317 )
a(2) = ( -2.965817 6.611990 -0.146615 )
a(3) = ( 1.157384 0.294294 3.513842 )
reciprocal axes: (cart. coord. in units 2 pi/a_0)
b(1) = ( 0.098478 0.043373 -0.036069 )
b(2) = ( 0.015762 0.157902 -0.018417 )
b(3) = ( 0.008738 0.010147 0.280861 )
PseudoPot. # 1 for Li read from file Li.pbe-n-van.UPF
Pseudo is Ultrasoft + core correction, Zval = 1.0
Generated by new atomic code, or converted to UPF format
Using radial grid of 751 points, 2 beta functions with:
l(1) = 1
l(2) = 1
Q(r) pseudized with 8 coefficients, rinner
= 1.000 1.000 1.000
PseudoPot. # 2 for N read from file N.pbe-van_ak.UPF
Pseudo is Ultrasoft, Zval = 5.0
Generated by new atomic code, or converted to UPF format
Using radial grid of 729 points, 4 beta functions with:
l(1) = 0
l(2) = 0
l(3) = 1
l(4) = 1
Q(r) pseudized with 8 coefficients, rinner =
0.800 0.800 0.800
PseudoPot. # 3 for H read from file H.pbe-van_ak.UPF
Pseudo is Ultrasoft, Zval = 1.0
Generated by new atomic code, or converted to UPF format
Using radial grid of 615 points, 1 beta functions with:
l(1) = 0
Q(r) pseudized with 8 coefficients, rinner = 0.800
atomic species valence mass pseudopotential
Li 1.00 6.94100 Li(
1.00)
N 5.00 14.00674 N ( 1.00)
H 1.00 1.00794 H ( 1.00)
No symmetry!
Cartesian axes
site n. atom positions (a_0 units)
1 Li tau( 1) = ( 2.6639799 4.4626230 1.4414460 )
2 Li tau( 2) = ( 1.5413893 1.8211812 0.0770139 )
3 N tau( 3) = ( 2.1626326 1.9176784 1.8319936 )
4 N tau( 4) = ( 2.0507651 4.3830957 -0.3106026 )
5 H tau( 5) = ( 2.1879002 0.8711414 1.8724490 )
6 H tau( 6) =
( 1.1765853 2.1450355 2.1090832 )
7 H tau( 7) = ( 2.9741083 3.9748254 -0.5760977 )
8 H tau( 8) = ( 2.1961052 5.4124675 -0.4458462 )
Self-consistent Calculation
iteration # 1 ecut= 140.00 Ry beta=0.70
CG style diagonalization
ethr = 1.00E-02, avg #
of iterations = 3.3
negative rho (up, down): 0.143E-04 0.000E+00
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