Computing Elastic Constants 2

Manual 08 for MD++
Computing elastic constants at nonzero temperature

Keonwook Kang, Seunghwa Ryu and Wei Cai

Jul 08 , 2009

---

In the previous manual, the elastic constants of bulk silicon of diamond cubic structure are computed at 0 K. In this manual, we compute the elastic constants at nonzero finite temperature using fluctuation-dissipation theorem.

${\begin{array}{rcl}\mathbf {P} &\equiv &\sum _{i}m_{i}\mathbf {v} _{i}=\mathrm {Const.} \\\mathbf {L} &\equiv &\sum _{i}\mathbf {r} _{i}\times m_{i}\mathbf {v} _{i}=\mathrm {Const.} \end{array}},$

Table 1. Elastic constants of DC Si. Potential Model : SW

T (K)	C11	C22	C33	C12	C13	C23	C44	C55	C66
300	149.41	149.36	149.45	76.26	76.18	76.24	62.45	75.00	54.93
625	146.35	146.29	146.35	75.80	75.77	75.71	53.72	50.03	46.98
888	142.74	142.86	142.84	75.07	75.17	74.99	60.78	53.54	56.76
1164	139.11	139.06	139.29	74.28	74.33	74.27	47.30	60.86	51.17
1477	135.02	134.84	134.69	73.84	73.85	73.80	44.96	41.41	47.66