IGNOU PHE 13 2026 - The potential energy of the Neon crystal is described by the expressio

Question

The potential energy of the Neon crystal is described by the expression:

$$U(r) = -4\varepsilon \left[ \left( \frac{\rho_0}{r} \right)^6 - \left( \frac{\rho_0}{r} \right)^{12} \right]$
where $\varepsilon = 3.12 \times 10^{-3}\text{ eV}$ and $\rho_0 = 2.82\text{ \AA}$ . Calculate the lattice parameter of the Neon crystal (fcc structure).

29 Jan 2026

Answer :

Word Count : 164

The potential energy of the Neon crystal is given by: [ U(r) = -4 \varepsilon \left[ \left( \frac{\rho_0}{r} \right)^6 - \left( \frac{\rho_0}{r} \right)^{12} \right] ] where (\varepsilon = 3.12 \times 10^{-3}\ \text{eV}) and (\rho_0 = 2.82\ \text{Å}). For equilibrium, the potential energy is minimum, so the derivative with respect to (r)

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