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atk:dft-1:2和dft-pps密度泛函方法计算电子态 [2020/06/01 21:06] – [DFT-PPS 法] xie.congwei | atk:dft-1:2和dft-pps密度泛函方法计算电子态 [2020/06/01 21:23] – [参数] xie.congwei | ||
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</ | </ | ||
==== Si、SiGe、Ge 的带隙和晶格常数 ==== | ==== Si、SiGe、Ge 的带隙和晶格常数 ==== | ||
+ | |||
+ | |||
+ | |||
+ | 如下所示,在 {{: | ||
+ | |||
+ | |||
+ | {{ : | ||
+ | |||
+ | DFT-PPS 法非常方便的一点是,它可以像普通 GGA 计算一样进行几何优化(力和应力最小化)–实际上,通常选择 DFT-PPS 参数提供高度精确半导体晶格常数的同时还能得到准确的带隙。 | ||
+ | |||
+ | 接下来,您将研究块体 Si 和 Ge 和一个简单的 50/50 SiGe 合金。这三个块体构型在脚本 [[https:// | ||
+ | |||
+ | 最后一个脚本如下所示。请注意该特定脚本中从第 2 到 12 行,从外部脚本导入了块体构型,并在这些构型和基组上建立了 Python 循环: | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | |||
+ | <code python> | ||
+ | 1 # -*- coding: utf-8 -*- | ||
+ | 2 from bulks import si, ge, sige | ||
+ | 3 | ||
+ | 4 | ||
+ | 5 | ||
+ | 6 | ||
+ | 7 | ||
+ | 8 | ||
+ | 9 | ||
+ | 10 | ||
+ | 11 for bulk_configuration, | ||
+ | 12 | ||
+ | 13 | ||
+ | 14 # ------------------------------------------------------------- | ||
+ | 15 # Calculator | ||
+ | 16 # ------------------------------------------------------------- | ||
+ | 17 | ||
+ | 18 na=9, | ||
+ | 19 nb=9, | ||
+ | 20 nc=9, | ||
+ | 21 ) | ||
+ | 22 | ||
+ | 23 | ||
+ | 24 | ||
+ | 25 ) | ||
+ | 26 | ||
+ | 27 | ||
+ | 28 | ||
+ | 29 | ||
+ | 30 ) | ||
+ | 31 | ||
+ | 32 | ||
+ | 33 | ||
+ | 34 | ||
+ | 35 | ||
+ | 36 | ||
+ | 37 # ------------------------------------------------------------- | ||
+ | 38 # Optimize Geometry | ||
+ | 39 # ------------------------------------------------------------- | ||
+ | 40 | ||
+ | 41 | ||
+ | 42 | ||
+ | 43 | ||
+ | 44 | ||
+ | 45 | ||
+ | 46 | ||
+ | 47 | ||
+ | 48 | ||
+ | 49 | ||
+ | 50 | ||
+ | 51 | ||
+ | 52 | ||
+ | 53 ) | ||
+ | 54 | ||
+ | 55 | ||
+ | 56 | ||
+ | 57 # ------------------------------------------------------------- | ||
+ | 58 # Bandstructure | ||
+ | 59 # ------------------------------------------------------------- | ||
+ | 60 | ||
+ | 61 | ||
+ | 62 | ||
+ | 63 | ||
+ | 64 ) | ||
+ | 65 | ||
+ | </ | ||
+ | |||
+ | |||
+ | 下载这 3 个脚本([[https:// | ||
+ | |||
+ | <code python> | ||
+ | $ atkpython pps.py > pps.log | ||
+ | $ atkpython pbe.py > pbe.log | ||
+ | </ | ||
+ | |||
+ | 每个作业执行大概需要 5 分钟。 | ||
+ | |||
+ | 然后使用脚本 [[https:// | ||
+ | |||
+ | Si 和 Ge 的 DFT-PPS 带隙与实验比较一致(黑色圆点;来自参考文献 <color # | ||
+ | |||
+ | 与未经校正的 PBE 相比,纯 Si 和 Ge 的 DFT-PPS 晶格常数也更接近实验(灰色方块)。 | ||
+ | |||
+ | {{ : | ||
+ | |||
==== 手动设置 DFT-PPS 参数 ==== | ==== 手动设置 DFT-PPS 参数 ==== | ||
+ | |||
+ | 当然,也可以手动设置 DFT-PPS 投影偏移参数,而不使用默认值。对于没有默认 DFT-PPS 参数(仅 Si 和 Ge 当前具有默认值)的元素,这将在 DFT-PPS 计算中特别有用。 | ||
+ | |||
+ | '' | ||
+ | |||
+ | <code python> | ||
+ | # | ||
+ | # Basis Set | ||
+ | # | ||
+ | # Basis set for Silicon | ||
+ | SiliconBasis_projector_shift = PseudoPotentialProjectorShift( | ||
+ | s_orbital_shift=21.33*eV, | ||
+ | p_orbital_shift=-1.43*eV, | ||
+ | d_orbital_shift=0.0*eV, | ||
+ | f_orbital_shift=0.0*eV, | ||
+ | g_orbital_shift=0.0*eV | ||
+ | ) | ||
+ | SiliconBasis = BasisGGASG15.Silicon_Medium(projector_shift=SiliconBasis_projector_shift) | ||
+ | |||
+ | # Basis set for Germanium | ||
+ | GermaniumBasis_projector_shift = PseudoPotentialProjectorShift( | ||
+ | s_orbital_shift=13.79*eV, | ||
+ | p_orbital_shift=0.22*eV, | ||
+ | d_orbital_shift=-2.03*eV, | ||
+ | f_orbital_shift=0.0*eV, | ||
+ | g_orbital_shift=0.0*eV | ||
+ | ) | ||
+ | GermaniumBasis = BasisGGASG15.Germanium_High(projector_shift=GermaniumBasis_projector_shift) | ||
+ | |||
+ | # Total basis set | ||
+ | basis_set = [ | ||
+ | SiliconBasis, | ||
+ | GermaniumBasis, | ||
+ | ] | ||
+ | </ | ||
+ | |||
+ | |||
+ | <WRAP center alert 100%> | ||
+ | === 警告 === | ||
+ | 选择适当的 DFT-PPS 参数可能是一件非常微妙的事情,并且通常需要数值优化程序。[[https:// | ||
+ | |||
+ | QuantumWise 不支持优化 DFT-PPS 参数。如果有默认参数的,我们通常建议用户使用默认值。 | ||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
- | ===== 参数 ===== | ||
+ | ===== 参考 ===== | ||
+ | * 英文原文:https:// | ||
+ | * [FMT08] Luiz G. Ferreira, Marcelo Marques, and Lara K. Teles. Approximation to density functional theory for the calculation of band gaps of semiconductors. //Phys. Rev. B//, 78:125116, Sep 2008. [[http:// | ||
+ | * [FMT11] (1, 2) Luiz G. Ferreira, Marcelo Marques, and Lara K. Teles. Slater half-occupation technique revisited: the LDA-1/2 and GGA-1/2 approaches for atomic ionization energies and band gaps in semiconductors. //AIP Adv//., 1(3): | ||
+ | * [LRS96] (1, 2, 3) M. Levinshtein, | ||
+ | * [WZ95] L.-W. Wang and A. Zunger. Local-density-derived semiempirical pseudopotentials. //Phys. Rev. B//, 51: |