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Article ID: 96 - Last Modified:

Using MacroModel, I receive an error message that includes the phrase "could not ALLOCATE". What does it mean, and what can I do?

"Could not allocate" usually means that the computation requested more memory than was available. Here are some possible approaches to resolve this issue.

  • Quit other applications if running on a workstation.
  • Use a substructure if your primary interest is the active site or only a portion of the structure—see The MacroModel Substructure Tab. This is the most popular method to reduce the memory demands of the computation.
  • Don't use solvation, instead use distance-dependent electrostatics with dielectric constant = 4.
  • Reduce the non-bonded cutoffs.
  • Try PRCG if using TN.
  • Try Prime, if appropriate.

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