Dependence of nanocrystal heat capacity on its size and shape under different P-T conditions

We have studied the changes in specific (per atom) heat capacity (isochoric Cv and isobaric Cp) when going from macro- to nanocrystal of cubic or rod-shape at different pressures (P) and temperatures (T). The calculations were made within the analytical method of the RP-model for the fcc gold. When calculating the heat capacity, other properties, related to it, were studied: Debye temperature (Θ), the first (γ) and second (q) Gruneisen parameters, the elastic modulus (BT), and the thermal expansion coefficient (αp). The pressure derivatives of these functions were also studied: Θ′(P), B′(P), αp′(P), Cv′(P), and Cp′(P). It was shown that with an isomorphic-isothermalisobaric decrease in the nanocrystal size, the Θ, q, BT functions decrease. In doing so, the next functions increase: Θ′(P), γ, αp, ⎥αp′(P)⎥, Ci(P), ⎥Ci′(P)⎥. It was shown that the function B′(P) can change its size dependence when the P–T conditions change. When the nanocrystal shape deviates from the energy-optimal shape, the size changes of the baric dependences increase.