mirror of https://gitlab.com/QEF/q-e.git
68 lines
2.8 KiB
Plaintext
68 lines
2.8 KiB
Plaintext
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This example shows how to use pw.x to calculate the total energy
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and the band structure of four simple systems (Fe, Al, Cu, Ni, Fe)
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in the non collinear case.
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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 for Fe (input=fe.scf.in,
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output=fe.scf.out). The number of computed bands is internally
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computed as equal to the number of electrons in the unit cell
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(16 in this case).
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2) make a band structure calculation for Fe (input=fe.band.in,
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output=fe.band.out).
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The variable nbnd is explicitly set = 16.
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The list of k points given in input is the list of point where the
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bands are computed, the k-point weight is arbitrary and is not used.
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3) make a self-consistent calculation for Fe with penalty functional
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where each component of the magnetization of the two atoms
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is constrained (input=fe.pen.in, output=fe.pen.out).
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Iron is a metal : the smearing technique is used for the
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calculation of the Fermi energy (a value for the broadening
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degauss is provided).
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4) make a self-consistent calculation for Fe with penalty functional
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where the angle between the direction of the magnetization of each atom
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and the z axis is constrained; mcons(1) = cosine of this angle.
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(input=fe.angl.in, output=fe.angl.out).
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5) make a self-consistent calculation for Fe with penalty functional
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where each component of the total magnetization is constrained;
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fixed_magnetization(ipol) = value of the magnetization.
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(input=fe.total.in, output=fe.total.out).
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6) make a self-consistent calculation for Cu (input=cu.scf.in,
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output=cu.scf.out).
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Copper is also a metal. In this case the tetrahedron method is used
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for the calculation of the Fermi energy. K-points are automatically
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generated.
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7) make a band structure calculation for Cu (input=cu.band.in,
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output=cu.band.out).
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The variable nbnd is explicitly set = 8.
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The list of k points given in input is the list of point where the
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bands are computed, the k-point weight is arbitrary and is not used.
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8) make a self-consistent calculation for Cu (input=cu.cg.in,
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output=cu.cg.out) with cg diagonalization.
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9) make a self-consistent calculation for Cu (input=cu.diis.in,
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output=cu.diis.out) with diis diagonalization.
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10) make a self-consistent calculation for Ni (input=ni.scf.in,
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output=ni.scf.out).
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Nickel is a magnetic metal. A local-spin-density calculation is
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performed by specifying nspin=2 and an initial guess for the
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magnetization of each atomic species. This initial guess is used to
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build spin-up and spin-down starting charges from superposition of
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atomic charges.
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11) make a band structure calculation for Ni (input=ni.band.in,
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output=ni.band.out).
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12) make a scf calculation of molecular oxygen relaxing the atoms.
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