Implements a Lennard-Jones 12-6 potential well associated with a boundary of the simulation cell for simulation of non-periodic dimensions. The form of the potential is given by
where \(r_{ij}\) is the distance between a particle and the wall, \(\varepsilon, \sigma\) are Lennard-Jones potential parameters, and \(r_{\rm cut}\) is cutoff distance.
FixWallLJ126(state,handle,groupHandle,origin,forceDir,dist,sigma,epsilon)
Arguments
Member data of the FixWallLJ126 potential may be modified directly via the Python interface; namely, ‘sigma’, ‘epsilon’, ‘dist’, ‘forceDir’, and ‘origin’ keywords are directly accessible from an instance of FixWallLJ126.
To modify any these parameters, simply assign them a new value of an appropriate type.
Example 1: creating an instance of FixWallLJ126
# create a simulation state to which we will add the fix
state = State()
# set the bounds of the state
state.bounds = Bounds(state, lo=Vector(0,0,0), hi=Vector(30,30,30))
# put the wall at (0,0,0)
origin = Vector(0,0,0)
# have the wall be acting in the +x direction
forceDir = Vector(1,0,0)
# cutoff distance of 15 units
dist = 15
# sigma and LJ
sigma = 2.4
epsilon = 1.0
# create an instance of the fix
fixWall = FixWallLJ126(state,"ljwall","all",origin,forceDir,dist,sigma,epsilon)
# activate the fix
state.activateFix(fixWall)
Example 2: Modifying the LJ constants of the above wall
# referring to the instances created above..
# change the sigma parameter
fixWall.sigma=3.0