Phonon computations
This is a quick sketch how to run a simple phonon calculation using DFTK.
Practical phonon computations have only seen rudimentary testing as of now. As of now we do not yet recommend relying on this feature for production calculations. Some of the limitations are:
- symmetries must be disabled (pass
symmetries=falseto the model) - only LDA functionals are supported
- non-linear core corrections from the pseudopotentials are not supported
- MPI parallelization over k-points is not supported (due to $k$ and $k+q$ interactions)
We appreciate any issues, bug reports or PRs.
First we run an SCF calculation.
using AtomsBuilder
using DFTK
using Printf
using PseudoPotentialData
pseudopotentials = PseudoFamily("cp2k.nc.sr.lda.v0_1.semicore.gth")
# Make sure to disable symmetries:
model = model_DFT(bulk(:Si); pseudopotentials, functionals=LDA(), symmetries=false)
basis = PlaneWaveBasis(model; Ecut=10, kgrid=[4, 4, 4])
scfres = self_consistent_field(basis, tol=1e-8);
nothing # hiden Energy log10(ΔE) log10(Δρ) Diag Δtime
--- --------------- --------- --------- ---- ------
1 -7.916328344253 -0.69 4.1 618ms
2 -7.921169486857 -2.32 -1.52 1.0 320ms
3 -7.921407284446 -3.62 -2.48 1.5 328ms
4 -7.921440912757 -4.47 -2.84 2.3 444ms
5 -7.921441781346 -6.06 -3.18 1.0 285ms
6 -7.921442007212 -6.65 -4.37 1.0 284ms
7 -7.921442022033 -7.83 -5.08 2.3 455ms
8 -7.921442022137 -9.98 -5.38 2.1 397ms
9 -7.921442022143 -11.22 -6.08 1.0 296ms
10 -7.921442022144 -12.14 -6.14 1.8 368ms
11 -7.921442022144 -12.71 -6.90 1.0 294ms
12 -7.921442022144 -13.82 -7.70 2.0 385ms
13 -7.921442022144 + -Inf -8.25 2.0 427ms
Next we compute the phonon modes at the q-point [1/4, 1/4, 1/4].
phret_q0 = @time DFTK.phonon_modes(scfres; q=[0.25, 0.25, 0.25]);
nothing # hideIter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.97s Non-interacting
1 0 1 1.03 15.1 13.0s
2 0 2 0.53 14.5 1.28s
3 0 3 -0.01 14.1 2.05s
4 0 4 -0.87 13.7 1.15s
5 0 5 -1.74 11.8 1.03s
6 0 6 -2.43 9.9 906ms
7 0 7 -3.33 8.9 848ms
8 0 8 -4.02 7.8 781ms
9 0 9 -5.04 6.4 679ms
10 0 10 -6.06 3.9 502ms
11 0 11 -7.08 2.2 399ms
12 0 12 -8.27 1.0 315ms
13 1 1 -7.53 17.8 1.88s Restart
14 1 2 -7.88 3.1 415ms
15 1 3 -8.69 2.1 360ms
19.2 2.15s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.46s Non-interacting
1 0 1 1.03 15.1 1.36s
2 0 2 0.53 14.5 1.25s
3 0 3 -0.01 14.1 1.23s
4 0 4 -0.87 13.8 1.19s
5 0 5 -1.74 11.8 1.07s
6 0 6 -2.43 10.0 934ms
7 0 7 -3.33 8.9 858ms
8 0 8 -4.02 7.8 785ms
9 0 9 -5.04 6.4 677ms
10 0 10 -6.06 3.9 495ms
11 0 11 -7.08 2.3 400ms
12 0 12 -8.27 1.0 320ms
13 1 1 -7.54 17.8 1.70s Restart
14 1 2 -7.89 3.1 404ms
15 1 3 -8.67 2.0 349ms
19.2 1.57s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.45s Non-interacting
1 0 1 1.03 15.1 2.21s
2 0 2 0.53 14.6 1.19s
3 0 3 -0.01 14.1 1.16s
4 0 4 -0.87 13.8 1.17s
5 0 5 -1.74 11.8 1.05s
6 0 6 -2.43 10.0 921ms
7 0 7 -3.33 8.9 848ms
8 0 8 -4.02 7.8 781ms
9 0 9 -5.04 6.4 672ms
10 0 10 -6.06 3.9 502ms
11 0 11 -7.08 2.3 397ms
12 0 12 -8.27 1.0 315ms
13 1 1 -7.54 17.9 1.71s Restart
14 1 2 -7.88 3.1 398ms
15 1 3 -8.65 2.1 347ms
19.2 1.57s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.44s Non-interacting
1 0 1 1.03 15.1 1.35s
2 0 2 0.53 14.5 1.24s
3 0 3 -0.01 14.1 1.21s
4 0 4 -0.87 13.7 1.20s
5 0 5 -1.74 11.8 1.08s
6 0 6 -2.43 9.9 925ms
7 0 7 -3.33 8.8 858ms
8 0 8 -4.02 7.8 786ms
9 0 9 -5.04 6.4 679ms
10 0 10 -6.06 3.9 504ms
11 0 11 -7.08 2.2 400ms
12 0 12 -8.27 1.0 315ms
13 1 1 -7.53 17.8 1.71s Restart
14 1 2 -7.89 3.1 400ms
15 1 3 -8.69 2.1 351ms
19.2 1.57s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 2.28s Non-interacting
1 0 1 1.03 15.1 1.30s
2 0 2 0.53 14.5 1.21s
3 0 3 -0.01 14.1 1.19s
4 0 4 -0.87 13.8 1.19s
5 0 5 -1.74 11.8 1.06s
6 0 6 -2.43 10.0 934ms
7 0 7 -3.33 8.9 854ms
8 0 8 -4.02 7.8 780ms
9 0 9 -5.04 6.4 677ms
10 0 10 -6.06 3.9 501ms
11 0 11 -7.08 2.3 398ms
12 0 12 -8.27 1.0 314ms
13 1 1 -7.54 17.8 1.70s Restart
14 1 2 -7.89 3.1 402ms
15 1 3 -8.68 2.0 348ms
19.2 1.57s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.44s Non-interacting
1 0 1 1.03 15.1 1.36s
2 0 2 0.53 14.6 1.23s
3 0 3 -0.01 14.1 1.22s
4 0 4 -0.87 13.8 1.20s
5 0 5 -1.74 11.8 1.07s
6 0 6 -2.43 10.0 934ms
7 0 7 -3.33 8.9 853ms
8 0 8 -4.02 7.8 784ms
9 0 9 -5.04 6.4 675ms
10 0 10 -6.06 3.9 501ms
11 0 11 -7.08 2.3 399ms
12 0 12 -8.27 1.0 316ms
13 1 1 -7.54 17.9 1.70s Restart
14 1 2 -7.88 3.1 398ms
15 1 3 -8.64 2.1 346ms
19.2 2.41s Final orbitals
139.581159 seconds (102.18 M allocations: 30.812 GiB, 4.21% gc time, 25.34% compilation time)
These are the final phonon frequencies:
for (i, ω) in enumerate(phret_q0.frequencies)
@printf("Mode %2d: %8.3f cm-1\n", i, ω .* DFTK.hartree_to_cm⁻¹)
endMode 1: 93.616 cm-1
Mode 2: 93.616 cm-1
Mode 3: 223.147 cm-1
Mode 4: 478.527 cm-1
Mode 5: 484.617 cm-1
Mode 6: 484.617 cm-1