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 -7.916323813826 -0.69 4.2 687ms
2 -7.921169768509 -2.31 -1.52 1.0 295ms
3 -7.921408352159 -3.62 -2.48 1.4 341ms
4 -7.921440905648 -4.49 -2.85 2.3 463ms
5 -7.921441779284 -6.06 -3.17 1.1 316ms
6 -7.921442007907 -6.64 -4.53 1.0 310ms
7 -7.921442022077 -7.85 -5.10 2.7 592ms
8 -7.921442022137 -10.22 -5.34 1.9 1.14s
9 -7.921442022143 -11.23 -5.98 1.1 299ms
10 -7.921442022144 -12.08 -6.05 1.5 332ms
11 -7.921442022144 -12.57 -7.09 1.0 299ms
12 -7.921442022144 -13.75 -7.32 2.1 451ms
13 -7.921442022144 + -15.05 -8.31 1.0 289ms
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 1.98s Non-interacting
1 0 1 1.03 15.1 12.8s
2 0 2 0.53 14.5 1.33s
3 0 3 -0.01 14.1 1.25s
4 0 4 -0.87 13.7 1.25s
5 0 5 -1.74 11.8 1.11s
6 0 6 -2.43 10.0 974ms
7 0 7 -3.33 8.9 885ms
8 0 8 -4.02 7.8 823ms
9 0 9 -5.04 6.4 698ms
10 0 10 -6.06 3.9 513ms
11 0 11 -7.08 2.3 419ms
12 0 12 -8.27 1.0 325ms
13 1 1 -7.53 17.8 1.95s Restart
14 1 2 -7.87 3.1 430ms
15 1 3 -8.67 2.1 351ms
19.2 2.23s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.53s Non-interacting
1 0 1 1.03 15.1 1.41s
2 0 2 0.53 14.5 1.28s
3 0 3 -0.01 14.1 1.27s
4 0 4 -0.87 13.8 1.24s
5 0 5 -1.74 11.8 1.97s
6 0 6 -2.43 10.0 940ms
7 0 7 -3.33 8.9 822ms
8 0 8 -4.02 7.8 770ms
9 0 9 -5.04 6.4 674ms
10 0 10 -6.06 3.9 500ms
11 0 11 -7.08 2.3 390ms
12 0 12 -8.28 1.0 322ms
13 1 1 -7.53 17.8 1.76s Restart
14 1 2 -7.88 3.1 414ms
15 1 3 -8.67 2.1 365ms
19.2 1.63s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.51s Non-interacting
1 0 1 1.03 15.1 1.42s
2 0 2 0.53 14.5 1.29s
3 0 3 -0.01 14.1 1.26s
4 0 4 -0.87 13.7 1.24s
5 0 5 -1.74 11.8 1.11s
6 0 6 -2.43 10.0 967ms
7 0 7 -3.33 8.9 880ms
8 0 8 -4.02 7.8 824ms
9 0 9 -5.04 6.4 706ms
10 0 10 -6.06 3.9 517ms
11 0 11 -7.08 2.3 415ms
12 0 12 -8.27 1.0 336ms
13 1 1 -7.53 17.9 1.77s Restart
14 1 2 -7.88 3.1 420ms
15 1 3 -8.65 2.1 360ms
19.2 1.64s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.50s Non-interacting
1 0 1 1.03 15.1 1.41s
2 0 2 0.53 14.5 1.29s
3 0 3 -0.01 14.1 2.11s
4 0 4 -0.87 13.7 1.18s
5 0 5 -1.74 11.8 1.05s
6 0 6 -2.43 9.9 938ms
7 0 7 -3.33 8.9 859ms
8 0 8 -4.02 7.8 799ms
9 0 9 -5.04 6.4 692ms
10 0 10 -6.06 3.9 510ms
11 0 11 -7.08 2.3 419ms
12 0 12 -8.28 1.0 324ms
13 1 1 -7.54 17.8 1.70s Restart
14 1 2 -7.88 3.1 393ms
15 1 3 -8.68 2.1 350ms
19.2 1.54s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 1.43s Non-interacting
1 0 1 1.03 15.1 1.34s
2 0 2 0.53 14.5 1.23s
3 0 3 -0.01 14.1 1.20s
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 915ms
7 0 7 -3.33 8.9 840ms
8 0 8 -4.02 7.8 774ms
9 0 9 -5.04 6.4 669ms
10 0 10 -6.06 3.9 495ms
11 0 11 -7.08 2.3 398ms
12 0 12 -8.28 1.0 311ms
13 1 1 -7.54 17.9 1.69s Restart
14 1 2 -7.88 3.1 396ms
15 1 3 -8.67 2.1 346ms
19.2 1.55s Final orbitals
Iter Restart Krydim log10(res) avg(CG) Δtime Comment
---- ------- ------ ---------- ------- ------ ---------------
20.0 2.30s Non-interacting
1 0 1 1.03 15.1 1.34s
2 0 2 0.53 14.5 1.23s
3 0 3 -0.01 14.1 1.24s
4 0 4 -0.87 13.7 1.22s
5 0 5 -1.74 11.8 1.09s
6 0 6 -2.43 10.0 949ms
7 0 7 -3.33 8.9 877ms
8 0 8 -4.02 7.8 814ms
9 0 9 -5.04 6.4 713ms
10 0 10 -6.06 3.9 508ms
11 0 11 -7.08 2.3 405ms
12 0 12 -8.27 1.0 330ms
13 1 1 -7.53 17.9 1.78s Restart
14 1 2 -7.88 3.1 410ms
15 1 3 -8.65 2.1 363ms
19.2 1.65s Final orbitals
140.279987 seconds (101.35 M allocations: 30.775 GiB, 3.65% gc time, 24.52% 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