Quick calculation of lattice parameter and unit cell volume for germanium?

[mxyplizk]

Homework Statement

Calculate d_hkl and v_c for the (111) direction of germanium.

Homework Equations

d_hkl=a/sqrt(h²+k²+l²)

v_c=unit cell volume=a₁dot(a2xa₃)

or

v_c=structure form factor/density

The Attempt at a Solution

d_hkl=a/sqrt(3)

I know how to solve this, I've just forgotten whether a refers to the lattice parameter (5.658 angstroms) or the atomic radius (1.52 angstroms).

for calculating the unit cell volume, I'm a little bit more lost. Could I just take the lattice parameter and cube it, since it's the side length of the unit cell? Thanks in advance.

 

[Astronuc]

The symbol 'a' refers to the lattice parameter, and if no other dimension is given, e.g., b and/or c, one may assume a cubic system.

https://www.ucl.ac.uk/~ucapahh/teaching/3C25/Lecture03s.pdf