CP2K Open Source Molecular Dynamics

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howto:dft_u [2023/11/23 09:25] – krackhowto:dft_u [2023/11/23 10:04] – Add citation krack
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 ===== EOS calculation for cubic FeO using DFT+U ===== ===== EOS calculation for cubic FeO using DFT+U =====
  
-The following ''CP2K'' input file shows how an equation of state (EOS) calculation for cubic FeO (space group #225, wüstite) can be performed with ''CP2K'' using DFT+U:+The following ''CP2K'' input file shows how an equation of state (EOS) calculation for cubic FeO (space group #225, wüstite) using ''2x2x2'' unit cells to account for the antiferromagnetic ordering along [111], can be performed with ''CP2K'' using DFT+U:
  
 <code cp2k> <code cp2k>
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 &END FORCE_EVAL &END FORCE_EVAL
 </code> </code>
 +The suggested Hubbard U<sub>eff</sub> value of 1.9 eV for iron using ''CP2K'' has been retrieved from the work of [[https://doi.org/10.1021/acs.est.7b01670|Kéri et al., ES&T 51, 10585-10594 (2017)]].
 +
 The calculations for different cell sizes, e.g. for 98% of the experimental cell volume, can be accomplished by changing the scaling factor ''f100'' in this line The calculations for different cell sizes, e.g. for 98% of the experimental cell volume, can be accomplished by changing the scaling factor ''f100'' in this line
 <code> <code>
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 @SET a         8.56*${f098} @SET a         8.56*${f098}
 </code> </code>
 +and likewise of other cell sizes. It recommended to start with a cell size close to the assumed minimum and to employ the wavefunction restart files consecutively for the larger and smaller cell sizes to avoid a convergence to different states for compressed and enlarged cells.
  
 +Running the example above while applying the scaling factors ''f094'' to ''f112'' using the CP2K version 2023.2 resulted in the following total energies:
 +<code>
 +# a [Angstrom]  Total energy [Hartree]
 +  8.385257      -4466.80963727
 +  8.444310      -4466.85496007
 +  8.502549      -4466.88640521
 +  8.560000      -4466.90536056
 +  8.616690      -4466.91306948
 +  8.672644      -4466.91064762
 +  8.727886      -4466.89906783
 +  8.782436      -4466.87923722
 +  8.836318      -4466.85199239
 +  8.889550      -4466.81806793
 +</code>
howto/dft_u.txt · Last modified: 2023/11/23 10:23 by krack