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Topic: Unrestricted Fragment in ADF  (Read 741 times)

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Offline ar_sachin

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Unrestricted Fragment in ADF
« on: December 17, 2021, 01:18:25 AM »
Dear all,

  I am trying to run a single point job in ADF. My molecule is a complex of Cerium (3+) ion, that is [Xe]4f1 configuration. I have so far split the complex into Ce(NO3)3 and ligand. The issue is ADF doesn't let you read the t21 file of an unrestricted fragment. So you have to run the fragment as a restricted one and then run the SINGLE POINT on the molecule as unrestricted, but you also need to mention the fragment (in this case the the cerium nitrate fragment) is to be considered as a unrestricted fragment.
  Would have been great if it worked. I keep getting the error that my fragment occupation doesn't match. I assume this is due to the fragment SINGLE POINT was run as a restricted calculation.

  I did manage to get around the issue by running the fragment SINGLE POINT as restricted and then in the full molecule SINGLE POINT calculation simply mentioning the OCCUPATION to be uneven, that is one extra electron in the ALPHA spin orbital.

  This gave me the result as expected. In the output of the final SINGLE POINT  (for the whole molecule) the extra electron is placed in the 4f orbital of the Cerium ion.

  I still wonder if this is the right approach.

  Hoping someone would nudge me in the right direction.

  with best
« Last Edit: December 17, 2021, 01:34:06 AM by ar_sachin »

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