mirror of https://gitlab.com/QEF/q-e.git
27 lines
1.2 KiB
Plaintext
27 lines
1.2 KiB
Plaintext
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This example illustrates how to calculate interatomic force
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constants (IFC) in real space for AlAs in zincblende structure.
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The calculation proceeds as follows (for the meaning of the cited input
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variables see the appropriate INPUT_* file)
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1) make a self-consistent calculation (input=alas.scf.in,
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output=alas.scf.out)
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2) make a phonon calculation for a uniform grid of q-points. We chose
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a 444 Monkhorst-Pack grid, not translated (nqte the variables
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nq, nq2, nq3). At Gamma, effective charges are automatically calculated
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(AlAs is a polar system). All dynamical matrices are saved with
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a different name ("fildyn" + 1-8), while "fildyn" + 0 contains the
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information on the q-point grid (type of grid and number of points)
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3) call program q2r.x to calculate IFC's in real space.
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All dynamical matrices are read and Fourier-transformed.
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The output file containing the force constants in a format suitable
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for program matdyn.x is alas444.fc.
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4) call program matdyn.x to recalculate phonons at any q-vector from
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previously calculated IFC's. See the header of matdyn.f90 for
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input documentation. Two different kind of calculations are
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performed: phonon dispersions along the Gamma-X line, phonon DOS
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