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° | Longrange | - | Set long range interactions |
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| | | Command | | Argument | | Datatype | | Default | | Min | | Max | |
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| Format: | | Longrange | Type = None | Coulomb |
| STRING | | - | | - |
| - | | |
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| Python: | | Longrange(Type) | | ||||||||||
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| Menu: | | Simulation > Force field | | ||||||||||
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| Related: | | ForceField , Interactions, Cutoff , ScaleForce, SimSpeed | | ||||||||||
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| Required: | |  | |
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The LongRange
command defines the treatment of long-range electrostatic interactions.
Long-range Coulomb interactions are calculated using the Particle Mesh Ewald (PME) algorithm, which requires a simulation cell with
periodic boundary conditions. All YAMBER force fields are optimized for use with long-range Coulomb forces. The accuracy of the PME calculations can be influenced with the
SimSpeed command.
The PME algorithm requires that the net charge
of the atoms in the simulation cell is zero. This is normally achieved by adding counter ions to the system using the Neutralization
Experiment. If this has not been done, YASARA will add a
'neutralizing plasma' that uniformly pervades the cell.
Example 1:
Longrange None
Do not calculate any long range interactions.
Example 2:
Longrange Coulomb
Calculate electrostatic Coulomb forces without cutoff.