My question is: the parameters delay and every of the command neigh_modify has such a relation (we denote timestep as M): delay is enforced to be a multiple of every, then when M delay = 0 is satified, M every = 0 is
automatically satisfied. Then this means only delay value is important to neighbor list update. Only when delay is set to zero, neighbor list updates according to the value of every--but this can be realized also by setiing delay to the expected value and every keeping its default value 1. So what I want to ask is: are there any cases where every has its unique usages which can not be substitutedd by delay--i.e., every is doing some work that delay cannot do?