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Feature #1498

g_dipoles does not work properly with ionic systems

Added by David van der Spoel over 5 years ago. Updated about 3 years ago.

Status:
New
Priority:
Low
Category:
analysis tools
Target version:
-
Difficulty:
uncategorized
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Description

g_dipoles tries to compensate for charged molecules by subtracting the net charge of each molecule. In (small) periodic systems the dipole is not well defined since it may change rather abruptly if one ion moves to another image.

History

#1 Updated by Erik Lindahl over 5 years ago

  • Tracker changed from Bug to Feature

David - any suggestions what should be done? If we think of a charge distribution in terms of expansions, I think the dipole should indeed be the first moment around the net charge, so then the subtraction seems correct?

Similarly, as far as I can tell the small system issue is a a problem with system size and PBC, not a problem with how g_dipoles calculates dipoles. It's not obvious to me that it is a problem that can be fixed, and even if it is, that sounds more like a feature. Feel free to change back to "bug" when there is a description of something that can be fixed!

#2 Updated by Mark Abraham about 3 years ago

  • Target version deleted (5.x)

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