## Elastic constants of sodium from molecular dynamics

Cagin-T and Ray-JR

Physical Review B**37**, 699-705(1988)

## ABSTRACT

We have performed molecular dynamics calculations of the adiabatic elastic
constants of sodium at three different temperatures, T = 198, 299, and
349 K. Our method uses fluctuation formulas appropriate for the
microcanonical ensemble which contain the elastic constants. In the
simulation we have used a first principles potential to model the
interaction between the sodium atoms. The results, including the shear
modulus C44, show good agreement with experiment at all three
temperatures. We have analyzed the contributions to the elastic constants
from different types of terms appearing in the fluctuation formula and
compared these contributions to other model-potential calculations.
The volume dependence in the potential has considerable effect on the
values of elastic constants. In comparison to some earlier calculations
which employed pair potentials with no volume dependence, the fluctuation
contributions to elastic constants C11 and C44 are noticeably large (20%
of the value of elastic constants in some cases). We find that the
elastic constants do not change by much for the different potential
cutoff ranges employed: 17.85, 23.72 and 27.70 bohrs.