Dear Kayahan,

I might be wrong (I cannot check right now, and the code might have changed in 
that part) but I seem to remember that by fixing occupations from input you 
only change the eigenvalues of the occupation matrix, not the eigenvectors. In 
other words, you are not forcing occupation 1 on the zy and xy states but on 
the third and fifth eigenstates of the occupation matrix (putting all other to 
zero). This is done after the first iteration. So, in order to understand how 
you want to modify it, you have to look at the occupation matrix for the 
species of interest after the first diagonalization.

Hope this helps.

Regards,

Matteo


On Feb 2, 2018, at 6:52 AM, Kayahan Saritas 
<saritaskaya...@gmail.com<mailto:saritaskaya...@gmail.com>> wrote:

Hi,

I have been using the starting_ns_eigenvalue keyword in order to force the 
system a specific occupation of orbitals at the initial steps of scf 
optimization. This is for the QE-5.3.0 (I know it is old version, I have to use 
this one for compatibility issues with a quantum Monte Carlo code, so some of 
the settings in my input may look unusual for the same reason). My input is the 
following below the post, it is basically AFM-II structure for rocksalt CoO, it 
has a some rhombohedral distortion that is observed around 0K.

I am following the starting_ns_eigenvalue(m,ispin,l) notation in pw.x manual, 
for example starting_ns_eigenvalue(1,1,1)=1 would mean that for species 1, 
majority spin in dz2 orbital, occupation is set to 1. I borrowed the order of m 
values from projwfc.x manual. So in the input, I intend to set occupations at 
dzy and dxy orbitals equal to one for species 1, minority spin (and species 2, 
majority spin). However, when I read the output, I get the following order 
(given below) during the first scf step. According to that 4th and 5th orbitals 
have an occupation of 1, not the 3rd and 5th that I asked in the input. Is it 
that QE grouping occupied and unoccupied orbitals together such that the order 
doesn’t matter or am I making a mistake in giving the right setup at the input. 
I would appreciate your feedback.

Thanks,
Kayahan
ORNL



———————————INPUT—————————————
&CONTROL
 calculation     = 'scf'
 outdir          = 'pwscf_output'
 prefix          = 'pwscf'
 pseudo_dir      = './'
/

&SYSTEM
 celldm(1)       = 1.0
 degauss         = 0.0005
 ecutwfc         = 350
 Hubbard_U(1)    = 5
 Hubbard_U(2)    = 5
 ibrav           = 0
 input_dft       = 'LDA'
 lda_plus_u      = .true.
 nat             = 4
 nosym           = .false.
 nspin           = 2
 ntyp            = 3
 occupations     = 'tetrahedra'

 starting_ns_eigenvalue(1,1,1)=0
 starting_ns_eigenvalue(2,1,1)=0
 starting_ns_eigenvalue(3,1,1)=1
 starting_ns_eigenvalue(4,1,1)=0
 starting_ns_eigenvalue(5,1,1)=1

 starting_ns_eigenvalue(1,2,1)=1
 starting_ns_eigenvalue(2,2,1)=1
 starting_ns_eigenvalue(3,2,1)=1
 starting_ns_eigenvalue(4,2,1)=1
 starting_ns_eigenvalue(5,2,1)=1

 starting_ns_eigenvalue(1,1,2)=1
 starting_ns_eigenvalue(2,1,2)=1
 starting_ns_eigenvalue(3,1,2)=1
 starting_ns_eigenvalue(4,1,2)=1
 starting_ns_eigenvalue(5,1,2)=1

 starting_ns_eigenvalue(1,2,2)=0
 starting_ns_eigenvalue(2,2,2)=0
 starting_ns_eigenvalue(3,2,2)=1
 starting_ns_eigenvalue(4,2,2)=0
 starting_ns_eigenvalue(5,2,2)=1

 tot_charge      = 0
 tot_magnetization = 0
/

&ELECTRONS
 conv_thr        = 1e-07
 electron_maxstep = 500
 mixing_beta     = 0.7
 mixing_fixed_ns = 8
/


ATOMIC_SPECIES
 Co1 58.933 Co.opt.upf
 Co2 58.933 Co.opt.upf
 O  15.999 O.opt.upf

ATOMIC_POSITIONS alat
 Co1      -5.65718220       0.00578461       0.01409542
 Co2      -5.64220976      -3.25742414      -4.63419238
 O       -8.49505366      -4.90328622      -6.94947095
 O       -2.78938403      -1.61155487      -2.31897499

K_POINTS automatic
 4 4 4  0 0 0

CELL_PARAMETERS cubic
      -2.82359317      -4.90156048       0.01386135
      -5.65717990       0.00578508       0.01412863
      -2.80366009      -1.61906839      -9.29643767


———————————OUTPUT—————————————
Modify starting ns matrices according to input values
--- enter write_ns ---
LDA+U parameters:
U( 1)     =  5.00000000
alpha( 1) =  0.00000000
U( 2)     =  5.00000000
alpha( 2) =  0.00000000
atom    1   Tr[ns(na)] (up, down, total) =   2.00000  5.00000  7.00000
 spin  1
  eigenvalues:
-0.000 -0.000  0.000  1.000  1.000
  eigenvectors:
0.000  0.005  0.001  0.003  0.990
0.157  0.589  0.003  0.246  0.005
0.244  0.029  0.681  0.043  0.004
0.563  0.020  0.314  0.103  0.001
0.036  0.357  0.002  0.605  0.000
  occupations:
0.994 -0.044 -0.049 -0.007  0.044
-0.044  0.251  0.107  0.161  0.386
-0.049  0.107  0.046  0.068  0.161
-0.007  0.161  0.068  0.104  0.250
0.044  0.386  0.161  0.250  0.605
 spin  2
  eigenvalues:
1.000  1.000  1.000  1.000  1.000
  eigenvectors:
0.000  0.001  0.990  0.002  0.008
0.124  0.140  0.006  0.475  0.255
0.584  0.009  0.004  0.015  0.388
0.200  0.367  0.000  0.104  0.328
0.091  0.485  0.000  0.404  0.020
  occupations:
1.000 -0.000 -0.000 -0.000 -0.000
-0.000  1.000  0.000  0.000 -0.000
-0.000  0.000  1.000  0.000  0.000
-0.000  0.000  0.000  1.000  0.000
-0.000 -0.000  0.000  0.000  1.000
atomic mag. moment =    -3.000000
atom    2   Tr[ns(na)] (up, down, total) =   5.00000  2.00000  7.00000
 spin  1
  eigenvalues:
1.000  1.000  1.000  1.000  1.000
  eigenvectors:
0.004  0.010  0.638  0.022  0.326
0.486  0.188  0.078  0.237  0.012
0.043  0.014  0.282  0.006  0.654
0.169  0.089  0.001  0.734  0.007
0.298  0.699  0.001  0.001  0.001
  occupations:
1.000  0.000 -0.000 -0.000  0.000
0.000  1.000 -0.000 -0.000 -0.000
-0.000 -0.000  1.000 -0.000 -0.000
-0.000 -0.000 -0.000  1.000 -0.000
0.000 -0.000 -0.000 -0.000  1.000
 spin  2
  eigenvalues:
-0.000 -0.000  0.000  1.000  1.000
  eigenvectors:
0.002  0.004  0.000  0.070  0.924
0.569  0.160  0.006  0.259  0.007
0.032  0.193  0.732  0.040  0.004
0.025  0.615  0.261  0.080  0.018
0.372  0.028  0.001  0.552  0.048
  occupations:
0.994  0.056 -0.005 -0.054 -0.014
0.056  0.265  0.107  0.155  0.395
-0.005  0.107  0.044  0.065  0.162
-0.054  0.155  0.065  0.098  0.239
-0.014  0.395  0.162  0.239  0.599
atomic mag. moment =     3.000000
N of occupied +U levels =   14.000000
--- exit write_ns —













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************************************************
Matteo Cococcioni
Theory and Simulation of Materials
École Polytechnique Fédérale de Lausanne






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