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[交流] 【求助】band structures using hybrid functionals 的Kpoints问题

http://cms.mpi.univie.ac.at/vasp-forum/forum_viewtopic.php?4.6633.10
band structures using hybrid functionals have to be calculated the following way:
-) First perform a selfconsistent Hartree-Fock/HSE calculation using a conventional KPOINTS file.
-) Copy the IBZKPT file to KPOINTS, and explicitely add all desired k-points along high-symmetry lines of the BZ that are needed for the bandstructure plot. Add the points at the end of the KPOINTS file, but set the weights of these added k-points to 0.
-) Do not forget to set the number of k-points in KPOINTS correctly (to the number of the k-points used in the standard mesh PLUS the number of the k-points along the lines), such that all k-points are used for the calculations.
-) NKRED can not be used.
-) Perform a second VASP run:
It is recommended to use the Davidson algorithm, since it converges that eigen energies at the new k-points fastest. Since VASP terminates when the total energy is converged to a certain threshold, it is important to force VASP to do a minimum number of steps, so that the orbitals at the new k-points are fully converged (note: since their weight is zero, they do not contribute to the total energy).
This can be done using e.g.

ALGO = N ; NELMIN = 5 ! Davidson, minimum 5 scf-steps
IBRION = 1 ! Use simple charge mixer, since
Pulay might blow up

-) The KS-eigenvalues of the states along the high-symmetry lines are written in OUTCAR, EIGENVAL, vasprun.xml; please cut the k-points required for the bandstructure from one of these files and proceed as usual (using p4vasp or any other graphics tool you usually use to produce bandstructure-plots)

Note: A Hartee-Fock calculation can NOT be continued from an existing CHGCAR file, since the non-local exchange is not determined by the charge density but by the density matrix and/or the KS-orbitals.


以上是官方给出的解释。


我的问题是:
1、-) Copy the IBZKPT file to KPOINTS, and explicitely add all desired k-points along high-symmetry lines of the BZ that are needed for the bandstructure plot. Add the points at the end of the KPOINTS file, but set the weights of these added k-points to 0.
按照这样的方法产生的Kpoints运行后提示Kpoints错误,不能读取。
2、这一句不知所云:(to the number of the k-points used in the standard mesh PLUS the number of the k-points along the lines), 没有理解怎么回事?



请问谁用hse的方法计算过能带结构,请show一下下你的Kpoints。
谢谢。

[ Last edited by wuli8 on 2010-12-1 at 21:04 ]
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江湖之远

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小木虫(金币+0.5):给个红包,谢谢回帖交流
gzqdyouxia(金币+1): 鼓励交流 2011-04-01 10:26:04
一楼的那个官方回复我有两点不太明白。
1)explicitely add all desired k-points along high-symmetry lines of the BZ that are needed for the bandstructure plot. Add the points at the end of the KPOINTS file,
这个是说把我们想要计算的沿高对称方向的K点自己加到KPOINTS的末尾部分,问题是自己计算这些K点的坐标是一件很麻烦的事情,像是有点能带计算可能需要计算八九十个K点,这要是自己一个一个算坐标,那可费劲了。我们之所以在VASP5.2之前的版本中使用的KPOINTS文件中使用Line-mode模式,就是因为vasp可以根据我们给出的高对称点,自行算出这些K点的坐标。
所以不知道哪位朋友知道有没有比较简单的方法可以得出沿高对称点的K点的坐标?
2) Perform a second VASP run: 在这个方法中自洽预算需要运行两遍,那我想知道第一遍自洽运算的作用是什么?我的想法是:如果我的KPOINTS文件事先就按照他上面所说的程序都设置好了(即Copy the IBZKPT file to KPOINTS, and explicitely add all desired k-points along high-symmetry lines of the BZ that are needed for the bandstructure plot. Add the points at the end of the KPOINTS file, but set the weights of these added k-points to 0. ),那我是不是直接运行一遍自洽运算就可以得出结果,不需要像一楼所说的那样进行两遍运算,因为毕竟这个运算是相当耗时间的。
有哪位高人可以指点一下?
12楼2011-03-31 21:31:26
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vimtex

银虫 (初入文坛)


show your KPOINTS instead.
2楼2010-12-02 00:00:21
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282926214

金虫 (小有名气)


引用回帖:
Originally posted by vimtex at 2010-12-02 00:00:21:
show your KPOINTS instead.

IBZKPT
是单机产生的?
3楼2010-12-02 08:37:51
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jghe

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zzy870720z(金币+2):谢谢指教 2010-12-04 21:36:29
wuli8(金币+100):感谢。我再试一试 2010-12-04 22:51:40
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例子,上半部分是Monkhorst Pack产生的K点,下面是高对称的K点,第二行总K点的数目是两部分的总和,画能带的时候只取下面高对称部分的本征值即可
4楼2010-12-04 21:15:41
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