Phonon computations

This is a quick sketch how to run a simple phonon calculation using DFTK. First we run an SCF calculation.

using AtomsBuilder
using DFTK
using PseudoPotentialData

pseudopotentials = PseudoFamily("cp2k.nc.sr.lda.v0_1.semicore.gth")
model  = model_DFT(bulk(:Si); pseudopotentials, functionals=LDA())
basis  = PlaneWaveBasis(model; Ecut=10, kgrid=[4, 4, 4])
scfres = self_consistent_field(basis, tol=1e-8);

n     Energy            log10(ΔE)   log10(Δρ)   Diag   Δtime
---   ---------------   ---------   ---------   ----   ------
  1   -7.916463056860                   -0.69    4.9    106ms
  2   -7.921210017892       -2.32       -1.52    1.0   53.9ms
  3   -7.921405585055       -3.71       -2.49    1.2   56.7ms
  4   -7.921440931071       -4.45       -2.84    2.5   74.3ms
  5   -7.921441632834       -6.15       -3.01    1.1   55.8ms
  6   -7.921442006013       -6.43       -4.44    1.0   55.4ms
  7   -7.921442021815       -7.80       -4.64    2.8   89.8ms
  8   -7.921442022124       -9.51       -5.23    1.0   55.8ms
  9   -7.921442022126      -11.95       -4.94    1.9   65.7ms
 10   -7.921442022143      -10.75       -5.86    1.0   55.8ms
 11   -7.921442022144      -12.13       -6.88    1.4   59.6ms
 12   -7.921442022144      -13.37       -6.81    2.6   84.7ms
 13   -7.921442022144      -14.10       -7.24    1.0   55.2ms
 14   -7.921442022144   +  -14.35       -7.87    1.0   56.6ms
 15   -7.921442022144      -14.75       -8.98    1.1   64.5ms

Next we compute the phonon modes at the q-point [1/4, 1/4, 1/4].

scfres = DFTK.unfold_bz(scfres)
phret_q0 = @time DFTK.phonon_modes(scfres; q=[0.25, 0.25, 0.25]);

Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      73.0   2.02s  Non-interacting
   1        0       1        0.31     52.3   2.39s
   2        0       2       -0.52     47.0   1.54s
   3        0       3       -2.40     41.7   1.43s
   4        0       4       -4.46     29.7   1.98s
   5        0       5       -6.46     17.4   760ms
   6        0       6       -8.91      4.0   427ms
   7        1       1       -7.83     55.7   2.05s  Restart
   8        1       2       -8.84      5.6   527ms
                                      72.8   2.11s  Final orbitals
Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      73.0   1.96s  Non-interacting
   1        0       1        0.31     52.3   1.78s
   2        0       2       -0.52     47.0   1.52s
   3        0       3       -2.40     41.7   1.37s
   4        0       4       -4.46     29.7   1.11s
   5        0       5       -6.46     17.4   765ms
   6        0       6       -8.91      4.0   430ms
   7        1       1       -7.83     55.7   2.12s  Restart
   8        1       2       -8.84      5.6   466ms
                                      72.8   2.09s  Final orbitals
Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      73.0   1.94s  Non-interacting
   1        0       1        0.31     52.3   1.78s
   2        0       2       -0.52     47.0   1.54s
   3        0       3       -2.40     41.7   1.40s
   4        0       4       -4.46     29.7   1.09s
   5        0       5       -6.46     17.4   1.67s
   6        0       6       -8.91      4.0   462ms
   7        1       1       -7.83     55.7   2.01s  Restart
   8        1       2       -8.84      5.6   469ms
                                      72.8   2.14s  Final orbitals
Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      73.0   1.95s  Non-interacting
   1        0       1        0.31     52.4   1.79s
   2        0       2       -0.52     47.0   1.53s
   3        0       3       -2.40     41.7   1.46s
   4        0       4       -4.46     29.7   1.11s
   5        0       5       -6.46     17.4   821ms
   6        0       6       -8.91      4.0   439ms
   7        1       1       -7.83     55.7   2.12s  Restart
   8        1       2       -8.84      5.6   468ms
                                      72.8   2.07s  Final orbitals
Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      72.9   1.93s  Non-interacting
   1        0       1        0.31     52.4   1.77s
   2        0       2       -0.52     47.0   1.61s
   3        0       3       -2.40     41.7   1.43s
   4        0       4       -4.46     29.7   1.07s
   5        0       5       -6.46     17.4   1.65s
   6        0       6       -8.91      4.0   391ms
   7        1       1       -7.83     55.7   1.99s  Restart
   8        1       2       -8.84      5.6   452ms
                                      72.8   2.00s  Final orbitals
Iter  Restart  Krydim  log10(res)  avg(CG)  Δtime   Comment
----  -------  ------  ----------  -------  ------  ---------------
                                      73.0   1.82s  Non-interacting
   1        0       1        0.31     52.4   1.69s
   2        0       2       -0.52     47.0   1.47s
   3        0       3       -2.40     41.7   1.37s
   4        0       4       -4.46     29.7   1.04s
   5        0       5       -6.46     17.4   747ms
   6        0       6       -8.91      4.0   413ms
   7        1       1       -7.83     55.7   2.00s  Restart
   8        1       2       -8.84      5.6   453ms
                                      72.8   1.98s  Final orbitals
 91.678301 seconds (92.55 M allocations: 80.307 GiB, 8.34% gc time, 1.24% compilation time: 100% of which was recompilation)

These are the final phonon frequencies:

phret_q0.frequencies

6-element Vector{Float64}:
 -0.0034981553566071073
 -0.0029774511571575963
 -0.0029774511568780564
  0.0043022306305581575
  0.004302230630641481
  0.004353201760953733