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小木虫论坛-学术科研互动平台 » 计算模拟区 » 量子化学 » 量化新手直通车 » castep中参数设置有个问题
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王梦ariel

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[求助] castep中参数设置有个问题

1、castep都是基于赝势平面波进行计算的吗？它里面的基组都是平面波基组，只是通过计算的Energy cutoff去调节基组的大小进行计算吗？然后赝势大小也等于截断能量吗？
2、看到一篇文献中，有这样一段描述，For each structure, the cell parameters and atomic positions
were relaxed using the density functional theory and
the generalized gradient approximation (GGA) to the exchange-
correlation functional as proposed by Perdew
et al. (1996, PBE functional). The ionic cores were described
by the ultrasoft pseudopotentials Fe.pbe-nd-rrkjus.
UPF, O.pbe-rrkjus.UPF, H.pbe-rrkjus.UPF and the
norm-conserving pseudopotential Al.pbe-rrkj.UPF from
http://www.quantum-espresso.org. The wave-functions
and the charge density were expanded in plane-waves with
40 and 480 Ry cutoffs, respectively (1 Ry = 13.606 eV).
Increasing the wave-functions cutoff to 60 Ry does not
change the total energy by more than 12 meV/atom and
provides the same relative variations of the lattice parameters.
For the electronic integration, the Brillouin zone was
sampled according to the Monkhorst–Pack scheme (Monkhorst
and Pack, 1976), using k-point grids consistent with
the supercell dimensions. k-point grids of 4  4  4 and
2  2  4 were used for the 1  1  1 and 2  2  1 rhombohedral
cells, respectively, while a 4  4  2 k-point grid
was used for the hexagonal unit-cell. This number of kpoints
is large enough to provide fully converged results.
Atomic relaxations were performed with the PWscf code，
没有搞清楚其中The wave-functions
and the charge density were expanded in plane-waves with
40 and 480 Ry cutoffs, respectively (1 Ry = 13.606 eV).中是说电荷密度的的截断能量是480Ry，还是什么？
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