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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 User Manual, section 4.3.3. Set up substructures using the 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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