mirror of https://gitlab.com/QEF/q-e.git
44 lines
1.7 KiB
Plaintext
44 lines
1.7 KiB
Plaintext
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This example shows how to use pw.x to perform constrained DFT+U
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calculations for FeO. The method is described in
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L. Ponet et al., npj Comput. Mater. 10, 151 (2024).
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In order to peform this calculation, Quantum ESPRESSO must be
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configured with the -D__OSCDFT flag: please see the documentation
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for more details at q-e/PW/Doc/INPUT_OSCDFT.def. Then one needs
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to prepare the OSCDFT input file (please see below), and execute
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the pw.x command with the flag -oscdft as follows:
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pw.x -oscdft < FeO.scf.in > FeO.scf.out
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This contrained approach is implemented inside the oxidation-state
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constrained DFT (OSCDFT) framework, with the option oscdft_type = 2.
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The contrained DFT+U calculation can be done in two ways:
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1. By providing the eigenvalues of the target occupation matrix (see run1)
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The syntax for this first option is the following:
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TARGET_OCCUPATION_NUMBERS
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I s m eigenvalue
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Here, I is the atomic index (according to ATOMIC_POSITIONS),
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s is the spin index (1 for up, and 2 for down),
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m is the index of the eigenvalue
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(e.g. from 1 to 5 for d electrons),
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'eigenvalue' is the target eignvalue of the occupation matrix.
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2. By providing the full target occupation matrix (see run2)
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The syntax for this first option is the following:
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TARGET_OCCUPATION_NUMBERS
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I s m m' occupation
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Here, I is the atomic index (according to ATOMIC_POSITIONS),
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s is the spin index (1 for up, and 2 for down),
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m and m' are the indices of the magnetic quantum numbers
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(e.g. from 1 to 5 for d electrons),
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'occupation' is the target occupation value.
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Please see the documentation at q-e/PW/Doc/INPUT_OSCDFT.def for the
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descritpion of all other input keywords in the OSCDFT input file.
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