Multi-site Compact-Like Discrete Breather in Discrete One-Dimensional Monatomic Chains

Multi-site compact-like discrete breathers in discrete one-dimensional monatomic chains are investigated by discussing a generalized discrete one-dimensional monatomic model. We obtain that the two-site compact-like discrete breathers with codes σ = 0,... ,0,1,1,0,... ,0 and codes σ=0,... , 0,1,-1,0,... ,0 can exist in discrete one-dimensional monatomic chain with quartic on-site and inter-site potentials. However, the former can only exist in hard quartic on-site potential and cannot exist in soft quartic on-site potential, whereas the latter is just reversed. All of the two-site Compact-like discrete breathers with codes σ.=0,....,0,1,1,0,.... ,0 and σ =0,... , 0,1,-1,0, .... ,0 cannot exist in a pure K₄ chain.