Pressure-induced softening as a common feature of framework structures with negative thermal expansion

Results of a series of molecular dynamics simulations of cubic siliceous zeolites suggest that pressure-induced softening---the phenomenon in which a material becomes progressively more compressible under pressure---is likely to be a common feature of framework materials that show negative thermal expansion. The correlation between the negative thermal expansion and the pressure-induced softening is investigated on the basis of thermodynamics.