mirror of https://gitlab.com/QEF/q-e.git
36 lines
1.7 KiB
Plaintext
36 lines
1.7 KiB
Plaintext
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This example illustrates how to use pw.x to perform molecular dynamics
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for an 8-atom cell of Si starting with compressed bonds along 111
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The calculation proceeds as follows (for the meaning of the cited input
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variables see the file 'INPUT_PW' in the directory 'pwdocs')
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1) make a MD run for Si in the diamond structure in a 2-atom cell starting
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with the bond along (111) slightly compressed. Use the Gamma point only.
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2) make a MD run for Si in the diamond structure in a 8-atom cell starting
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with the bond along (111) slightly compressed. Use the Gamma point only.
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Note that the two calculations do not give exactly the same results
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because the BZ samplig is different.
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3) make a MD run for Si in the diamond structure in a 2-atom cell starting
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with the bond along (111) slightly compressed. Use the Gamma and the
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3 X points for the BZ sampling.
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It should give the same result as the calculation with 8 atoms (clearly
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the total energy is 4 times larger)
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In all the three calculation above:
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calculation='md' specifies that a MD run is performed.
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dt=20 defines the time step in (Rydberg) atomic unit of time.
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The mass of each type of atom is specified in the cards ATOMIC_SPECIES
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(for Si, 28.086 is the atomic mass in a.m.u.)
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nstep=100 is the number of steps in the MD run.
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potential_extrapolation='wfc2' meansd that starting guess for the
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potential and the wavefunctions at the new atomic positions will
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be extrapolated from previous history.
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nosym=.true. states that symmetry should not be used in the MD run.
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Additional variables (such as temperature) could be set in a MD run.
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Refer to INPUT_PW for their meaning.
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