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wuli8

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[交流] 【已经完成】Optical properties and density functional perturbation theory 的翻译

vasp5.2已经出来一段时间了，vasp5.2增加了的新功能，例如：可以直接计算光学性质等。但是具体计算的技术细节还有很多人不清楚。怎么办？先从最基础的抓起———说明书。

但是E文的说明书对我们的理解有n多障碍。所以特向大家vasp求助说明书的翻译。

这里以Optical properties and density functional perturbation theory (PT)一节的翻译为例。其余的章节待续……

Optical properties and density functional perturbation theory (PT)一节的目录

http://cms.mpi.univie.ac.at/vasp/vasp/Optical_properties_density_functional_perturbation_theory_PT.html
1、LOPTICS: frequency dependent dielectric matrix （已经完成，感谢franch悬赏50金币，1st强帖1个）

2、CSHIFT: complex shift in Kramers-Kronig transformation （已经完成，感谢lzl8181）

3、LNABLA: transversal gauge （已经完成，感谢lzl8181）

4、LEPSILON: static dielectric matrix, ion-clamped piezoelectric tensor and the Born effective charges using density functional perturbation theory （已经完成，感谢lzl8181 ）

5、LRPA: local field effects on the Hartree level (RPA) （已经完成，感谢franch）

6、Vibrational frequencies, relaxed-ion static dielectric tensor and relaxed-ion piezoelectric tensor(已经完成，感谢lzl8181)

所有需要翻译的word版下载：（1-6）
http://d.namipan.com/d/0897b314d ... d6342c1719ae4a60000

回帖方式：
请下载word版的原文，然后逐句翻译。翻译完成后请发送您的中英对照作品到wuli8@163.com，然后回帖。如有重复则奖励最先发送邮件的翻译者。
您的翻译作品将整理后发帖。

翻译的作品如果再附加上自己的心得和体会等内容更有100金币的大礼包赠送。

人人为我，我为人人！期待着您的作品！谢谢！

[ Last edited by wuli8 on 2010-12-7 at 23:45 ]

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1楼2010-11-13 23:46:02

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wuli8

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5、LRPA: local field effects on the Hartree level (RPA)
LRPA= .TRUE. |.FALSE.

Default: LRPA= .FALSE.

Usually local field effect are included on the Hartree level only (LRPA=.TRUE.). This means that cell periodic microscopic changes of the local potential related to the change of the Hartree potential are included. If LRPA=.FALSE., however, changes of the Hartree potential and the exchange correlation potential are included. This usually increases the dielectric constants. The final values for the dielectric matrix can be found in the OUTCAR file after the lines.

MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in RPA (Hartree))

For LRPA=.FALSE. the dielectric matrix is written after the lines:
MACROSCOPIC STATIC DIELECTRIC TENSOR (including local field effects in DFT)

The dielectric constants without local field effects is always determined (irregardless of LRPA). The piezoelectric tensors and the Born effective charges as well as the ionic contributions the to dielectric tensor are only calculated for LRPA=.FALSE.

11楼
franch 的翻译：（感谢ta）

Hartree近似下的局域场效应
LRPA= .TRUE. |.FALSE.
Default: LRPA= .FALSE.
一般情况，局域场效应只在Hartree近似条件下被考虑到。也就是说和hartree势能相关的局域势能的晶胞周期性微变化被考虑了。如果 LRPA=FALSE，那么，hartree势能和交换相关势能都将被考虑到。这经常会使得介电常数增加。介电矩阵的最终值可以在OUTCAR文件的最后几行找到。
宏观静电介电张量（考虑无归相近似下的局域场效应（Hartree））

对于 LRPA=.FALSE，介电矩阵被写在最后面几行。

默认情况下，一般会给出不考虑局域场效应的介电常数（与LRPA无关）。压电张量和波尔有效电荷与离子部分对介电张量的贡献只有在LRPA=.FALSE情况下才被计算进去。

[ Last edited by wuli8 on 2010-11-18 at 12:42 ]

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6楼2010-11-13 23:48:38

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wuli8

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需要翻译的原文如下1、LOPTICS: frequency dependent dielectric matrix

LOPTICS: frequency dependent dielectric matrix
LOPTICS= .TRUE. | .FALSE.

Default: LOPTICS=.FALSE.

If LOPTICS=.TRUE., VASP calculates the frequency dependent dielectric matrix after the electronic ground state has been determined. The imaginary part is determined by a summation over empty states using the equation:

(54)

where the indices  and  refer to conduction and valence band states respectively, and  is the cell periodic part of the orbitals at the k-point . The real part of the dielectric tensor  is obtained by the usual Kramers-Kronig transformation

(55)

where  denotes the principle value. The method is explained in detail in Ref. [84] (Eq. (15), (29) and (30) in Ref. [84]). The complex shift  is determined by the parameter CSHIFT (Sec. 6.65.2).
Note that local field effects, i.e. changes of the cell periodic part of the potential are neglected in this approximation. These can be evaluated using either the implemented density functional perturbation theory (see Sec. 6.65.4) or the GW routines (see Sec. 6.66). Furthermore the method selected using LOPTICS=.TRUE. requires an appreciable number of empty conduction band states. Reasonable results are usually only obtained, if the parameter NBANDS is roughly doubled or tripled in the INCAR file with respect to the VASP default. Furthermore it is emphasized that the routine works properly even for HF and screened exchange type calculations and hybrid functionals. In this case, finite differences are used to determine the derivatives of the Hamiltonian with respect to .

Note that the number of frequency grid points is determined by the parameter NEDOS (see Sec. 6.36). In many cases it is desirable to increase this parameter significantly from its default value. Values around 2000 are strongly recommended.

1、LOPTICS:频率依赖的介电矩阵
LOPTICS= .TRUE. | .FALSE.
Default: LOPTICS=.FALSE.
如果LOPTICS=.TRUE.，在得到电子基态后VASP会计算频率依赖的介电矩阵。其虚部由下面的方程对空态积分得到

其中下标  和分别对应于导带和介带电子态，  是在确定K-point点轨道的晶胞周期性部分。介电张量的实部由克拉末-克朗尼格变换得到。
(55)
其中  代表主值。这方法的原理在文献84(文献84中的方程(15), (29)和 (30))中有具体解释。复数平移量  有参数CSHIFT决定。(Sec. 6.65.2).
需要注意，局域场效应，也就是势能的晶胞周期性部分在这种近似中被忽略了。这些效应可以通过密度泛函微扰理论(see Sec. 6.65.4)或者GW(see Sec. 6.66)程序算出。此外，选取LOPTICS=.TRUE时，这方法需要相当可观数量的空导带电子态。合理的结果只能是在INCAR文件中的NBANDS 值大概取VASP默认值的2，3倍时得到。另外，这里需要重点指出的是，hartree-fock，屏蔽交换类型的计算和杂化泛函的程序。这种情况下，用有限差分法来决定哈密顿量关于的导数。
需要注意的是，频率网格点的数量由参数NEDOS(see Sec. 6.36)决定。在很多情况下需要增加这个参数值，显著的高于它的默认值。2000左右的数值是我们强烈推荐的。

word 版http://pic.muchong.com/file.php?id=138

[ Last edited by wuli8 on 2010-11-18 at 23:11 ]

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2楼2010-11-13 23:47:23

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wuli8

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需要翻译的原文如下2、CSHIFT: complex shift in Kramers-Kronig transformation

CSHIFT= [real]

Default: CSHIFT=0.1

The implemented Kramers-Kronig transformation uses a small complex shift  CSHIFT in Eq. (6.49). The default for this shift is 0.1, which is perfectly acceptable for most calculations and causes a slight smoothening of the real part of the dielectric function. If the gap is very small (i.e. approaching two times CSHIFT), slight inaccuracies in the static dielectric constant are possible, which can be remedied by decreasing CSHIFT. If CSHIFT is further decreased, it is strongly recommended to increase the parameter NEDOS to values around 2000 (see Sec. 6.36).CSHIFT: 克拉末-克朗尼格变换中的复杂（数？）移动
CSHIFT= [实数]    Default: CSHIFT=0.1  缺省设置值：0.1
在对Eq. (6.49)实施克拉末-克朗尼格变换时使用了一个小的复数移动  CSHIFT。缺省设置值为0.1，这个值对大多数计算可得出可接受的结果，同时可使介电函数的实部变得平滑。如果能隙很小（也就是接近CSHIFT的2倍），可能会导致计算所得的静态介电函数稍显不准确，这可以通过减小CSHIFT而得到修正。如果CSHIFT进一步减小，强烈推荐增大参数NEDOS至2000左右(see Sec. 6.36)
本文来自: 小木虫论坛 http://muchong.com/bbs/viewthread.php?tid=2592318&fpage=1&view=&highlight=&page=2

[ Last edited by wuli8 on 2010-12-6 at 23:34 ]

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3楼2010-11-13 23:47:30

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wuli8

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需要翻译的原文如下3LNABLA: transversal gauge
LNABLA= .TRUE. | .FALSE.

Default: LNABLA=.FALSE.

Usually VASP uses the longitudinal expression for the frequency dependent dielectric matrix as described in the preceeding section (see. 6.65.1). It is however possible to switch to the computationally somewhat simpler transversal expressions by selecting LNABLA=.TRUE. (in this case Eq. (17) and (20) in Ref. [84]). In this simplification the imaginary part of the macroscopic dielectric function is given by

(56)

Except for the purpose of testing, there is however hardly ever a reason to use the transversal expression, since it is less accurate.[84]

[ Last edited by wuli8 on 2010-11-14 at 00:44 ]

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4楼2010-11-13 23:48:10

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