Answer
$2.21\times 10^{-44}kg \cdot m^2$.
Work Step by Step
The two atoms are identical. Their center of mass is halfway between them.
Each atom has the given mass m, and is at a distance of (0.447 nm)/2 from the center of mass.
$$I=2 m(\frac{L}{2})^2=2.21\times 10^{-44}kg \cdot m^2$$
