Artificial Material with Negative Thermal Expansion: A Simple   Geometrical Approach
  In the paper we report the modeling and design of material which has a negative thermal expansion (NTE). The basic assumption is a potential between the atoms in the material can be approximated by a Lennard-Jones potential (6-12) and the dominant interaction is only between nearest neighbors. We show that the material formed by alternating atomic layers wherein each layer contains a type of atom, and geometry of the arrangement of atoms is triangular, may experience an NTE when sigma_AA = sigma_BB = sigma_AB, epsilon_AA = epsilon_BB < epsilon_AB/4 are satisfied, where sigma_ij and epsilon_ij are Lennard-Jones parameters 
Mikrajuddin Abdullah
cond-mat.mtrl-sci