  We have investigated anomalous lattice behavior of metal organic framework
compound AgC8N5on application of pressure and temperature using ab-initio
density functional theory calculations. The van der Waals dispersion
interactions are found to play an important role in structural optimization and
stabilization of this compound. Our ab-initio calculations show negative linear
compressibility (NLC) along the c-axis of the unit cell. The ab-initio lattice
dynamics as well as the molecular dynamics simulations show large negative
thermal expansion (NTE) along the c-axis. The mechanism of NLC and NTE along
the c-axis of the structure is governed by the dynamics of Ag atoms in the a-b
plane. The NLC along the c-axis drives the NTE along that direction.
