<div dir="ltr"><div>Dear users,</div><div>I'm running a phonon calculation for the following script. The output file has a message which states "Eigenvectors exchange needed". Can I know what this means? Unfortunately, no such query was posted/answered earlier on the forum so any related help is appreciated.</div><div>Input:</div><div>&control<br>    calculation = 'scf',<br>    prefix = '176.83368'<br>    tprnfor=.true.<br>    tstress=.true.<br>    outdir = '/home/'<br>    pseudo_dir = '/home/'<br> /<br> &system<br>    ibrav =  0, <br>    nat =  20, <br>    ntyp = 3,<br>    ecutwfc = 80,<br>/    <br>&electrons<br>    diagonalization='david'<br>    mixing_mode = 'plain'<br>    mixing_beta = 0.7<br>    conv_thr =  1.0d-12<br>/<br><br>ATOMIC_SPECIES<br>   Ca 40.078  Ca.pz-spn-kjpaw_psl.1.0.0.UPF<br>   Si 28.0855 Si.pz-n-kjpaw_psl.0.1.UPF<br>    O 15.999   O.pz-n-kjpaw_psl.0.1.UPF<br><br>K_POINTS (automatic)<br>   4 4 4 1 1 1 <br><br>CELL_PARAMETERS (angstrom)<br>   4.977117627   0.000000000   0.000000000<br>  -0.000000000   4.977117627   0.000000000<br>   0.000000000   0.000000000   7.138536283<br><br>ATOMIC_POSITIONS (crystal)<br>Ca            0.0000000000        0.5000000000        0.2500000184<br>Ca            0.0000000000        0.5000000000        0.7499999816<br>Ca            0.5000000000        0.0000000000        0.2500000184<br>Ca            0.5000000000        0.0000000000        0.7499999816<br>Si            0.0000000000        0.0000000000       -0.0000000000<br>Si            0.0000000000        0.0000000000        0.5000000000<br>Si            0.5000000000        0.5000000000        0.5000000000<br>Si            0.5000000000        0.5000000000       -0.0000000000<br>O             0.2219920219        0.2780079799        0.0000000000<br>O             0.7780079481        0.7219920501       -0.0000000000<br>O             0.7219920501        0.2219920219        0.0000000000<br>O             0.2780079799        0.7780079481        0.0000000000<br>O             0.7780079429        0.2780079736        0.5000000000<br>O             0.2219920271        0.7219920564        0.5000000000<br>O             0.2780079736        0.2219920271        0.5000000000<br>O             0.7219920564        0.7780079429        0.5000000000<br>O             0.0000000000        0.0000000000        0.2500000059<br>O             0.0000000000        0.0000000000        0.7499999941<br>O             0.5000000000        0.5000000000        0.7499999931<br>O             0.5000000000        0.5000000000        0.2500000069<br><br>---<br>&inputph<br>   tr2_ph=1.0d-12,<br>   prefix='176.83368',<br>   fildyn='176.83368.dyn',<br>   ldisp=.TRUE.<br>   nq1=2, nq2=2, nq3=2,<br>/<br><br>&input<br>  fildyn='176.83368.dyn',<br>  zasr='simple',<br>  flfrc='176.83368.fc'<br>/</div><div><br></div><div><br></div><div>Section of output where message appears:</div><div><br></div><div>     Dynamical matrices for ( 2, 2, 2)  uniform grid of q-points<br>     (   6 q-points):<br>       N         xq(1)         xq(2)         xq(3) <br>       1   0.000000000   0.000000000   0.000000000<br>       2   0.000000000   0.000000000  -0.348609115<br>       3   0.000000000  -0.500000000   0.000000000<br>       4   0.000000000  -0.500000000  -0.348609115<br>       5  -0.500000000  -0.500000000   0.000000000<br>       6  -0.500000000  -0.500000000  -0.348609115<br>Eigenvectors exchange needed   13   19<br>Eigenvectors exchange needed   15   21<br>Eigenvectors exchange needed   17   23<br>Eigenvectors exchange needed   19   20<br>Eigenvectors exchange needed   21   22<br>Eigenvectors exchange needed   23   24<br>Eigenvectors exchange needed   37   49<br>Eigenvectors exchange needed   39   51<br>Eigenvectors exchange needed   41   53<br>Eigenvectors exchange needed   43   55<br>Eigenvectors exchange needed   45   57<br>Eigenvectors exchange needed   47   59<br>Eigenvectors exchange needed   49   50<br>Eigenvectors exchange needed   51   52<br>Eigenvectors exchange needed   53   54<br>Eigenvectors exchange needed   55   56<br>Eigenvectors exchange needed   57   58<br>Eigenvectors exchange needed   59   60<br>Eigenvectors exchange needed   13   22<br>Eigenvectors exchange needed   15   24<br>Eigenvectors exchange needed   17   26<br>Eigenvectors exchange needed   19   28<br>Eigenvectors exchange needed   21   30<br>Eigenvectors exchange needed   23   30<br>Eigenvectors exchange needed   25   30<br>Eigenvectors exchange needed   27   30<br>Eigenvectors exchange needed   29   30<br>Eigenvectors exchange needed   43   52<br>Eigenvectors exchange needed   45   54<br>Eigenvectors exchange needed   47   56<br>Eigenvectors exchange needed   49   58<br>Eigenvectors exchange needed   51   60<br>Eigenvectors exchange needed   53   60<br>Eigenvectors exchange needed   55   60<br>Eigenvectors exchange needed   57   60<br>Eigenvectors exchange needed   59   60<br>Eigenvectors exchange needed   15   20<br>Eigenvectors exchange needed   17   22<br>Eigenvectors exchange needed   19   24<br>Eigenvectors exchange needed   21   24<br>Eigenvectors exchange needed   23   24<br>Eigenvectors exchange needed   39   50<br>Eigenvectors exchange needed   41   52<br>Eigenvectors exchange needed   43   54<br>Eigenvectors exchange needed   45   56<br>Eigenvectors exchange needed   47   58<br>Eigenvectors exchange needed   49   60<br>Eigenvectors exchange needed   51   60<br>Eigenvectors exchange needed   53   60<br>Eigenvectors exchange needed   55   60<br>Eigenvectors exchange needed   57   60<br>Eigenvectors exchange needed   59   60<br>Eigenvectors exchange needed   15   23<br>Eigenvectors exchange needed   17   25<br>Eigenvectors exchange needed   19   27<br>Eigenvectors exchange needed   21   29<br>Eigenvectors exchange needed   23   24<br>Eigenvectors exchange needed   25   26<br>Eigenvectors exchange needed   27   28<br>Eigenvectors exchange needed   29   30<br>Eigenvectors exchange needed   45   53<br>Eigenvectors exchange needed   47   55<br>Eigenvectors exchange needed   49   57<br>Eigenvectors exchange needed   51   59<br>Eigenvectors exchange needed   53   54<br>Eigenvectors exchange needed   55   56<br>Eigenvectors exchange needed   57   58<br>Eigenvectors exchange needed   59   60<br><br>     Calculation of q =    0.0000000   0.0000000   0.0000000<br><br>     &control                                                                   <br><br>     bravais-lattice index     =            0<br>     lattice parameter (alat)  =       9.4054  a.u.<br>     unit-cell volume          =    1193.3328 (a.u.)^3<br>     number of atoms/cell      =           20<br>     number of atomic types    =            3<br>     kinetic-energy cut-off    =      80.0000  Ry<br>     charge density cut-off    =     320.0000  Ry<br>     convergence threshold     =      1.0E-12<br>     beta                      =       0.7000<br>     number of iterations used =            4<br>     Exchange-correlation= PZ<br>                           (   1   1   0   0   0   0   0)<br><br><br></div></div>