59 lines
2.3 KiB
Plaintext
59 lines
2.3 KiB
Plaintext
** The objective of the test problems in this directory
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is the following twofold:
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- verify the implementation of the LAMMPS' SPIN package by
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comparing its results to well-known analytic results, or
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to simple test problems,
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- provide users with simple comparisons, allowing them to
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better understand what is implemented in the code.
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The LAMMPS input file (test-*) can be modified, as well as the
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associated python script, in order to try different comparisons.
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All scripts can be run by executing the shell script from its
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directory. Example:
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./run-test-exchange.sh from the validation_damped_exchange/
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directory.
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** Below a brief description of the different validation
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problems:
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- validation_damped_precession:
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simulates the damped precession of a single spin in a magnetic
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field.
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Run as: ./run-test-prec.sh
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Output: x, y and z components of the magnetization, and
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magnetic energy.
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- validation_damped_exchange:
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simulates two spins interacting through the exchange
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interaction. The parameters in the LAMMPS input script
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(test-spin-precession.in) are calibrated to match the
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exchange definition in the python script (llg_exchange.py).
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Run as: ./run-test-exchange.sh
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Output: average magnetization resulting from the damped
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precession of the two interacting spins. Also plots the
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evolution of the magnetic energy.
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- validation_langevin_precession:
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simulates a single spin in a magnetic field and in contact
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with a thermal bath, and compares the statistical averages of
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the output to the analytical result of the Langevin function.
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Run as: ./run-test-prec.sh
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Output: statistical average of the z-component of the
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magnetization (along the applied field) and of the magnetic
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energy versus temperature. Comparison to the Langevin function
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results (computed by the python script).
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Note: This example is a reworked version of a test problem
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provided by Martin Kroger (ETHZ).
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- validation_nve:
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simulates a small assembly of magnetic atoms (54). The atoms are
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coupled by an exchange interaction and a mechanical potential
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(EAM here).
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This example represents an NVE run: the total energy of the
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system is preserved, whereas the spin and lattice energy
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reservoirs are exchanging energy.
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Run as: ./run-test-nve.sh
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Output: res_lammps.dat contains the data. The results are displayed
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by nve_spin_lattice.pdf.
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