Dear All,
I studied the curve of the Free Energy corresponding to the
lattice. With proper pseudopotential and basis (from PRL 92, 175503), I
fixed the supercell with MD.variableCell F, CG step=0. And large K points
18*18*18, large meshcutoff of 400. Ry to get fine real grid(0.08 a.u.), both
large and small ElectronTempreture , default DM.Tolerance (1.d-3).
Then I come to this problem: the figure of E-A (Where a is different
lattice constant) is smooth when the difference between lattice constant is
0.01 a.u. as follow
cid:[email protected]
I gained the Bulkmodulus quite agree with the description in PRL 92,
175503, i.e. 1.80 Mbar.
However, when I tried to make denser calculation, say 0.001 a.u. as the
difference, I found a terrible curve.
cid:[email protected]
I tried several methods: increase K points, decrease the smearing broaden by
low ElectronTempreture, use smaller real grid by enlarge Meshcutoff.
However, nothing changed, the figure was still ugly. I even changed
different pseudopotential and basis and repeat last process, and there still
appeared no fine curve.
Any advice is OK. I will be really grateful. Thanks in advance.
Best
Leila
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