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snowmami

新虫 (正式写手)


[交流] 【求助】wien2k-FAQ实在是看不懂,哪位高手帮我翻译下?

下面的文字对我很重要,但实在看不懂,很着急,难者不会,会者不难,各位高手能否帮忙翻译下?
WIEN2k-FAQ: Setup of antiferromagnetic calculations?

©2001 by P. Blaha, K. Schwarz and J. Luitz

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      FAQ Index

Setup of antiferromagnetic calculations requires some tricks which will be described below:

   1. You need to construct a unit cell which allows for the desired AF ordering. E.g. for bcc Cr you have to put "P" lattice and 2 NON-equivalent atoms at (0,0,0) and (0.5,0.5,0.5). In order to make nn working properly, you should also specify different labels in the "name(3:10)"-field for the two AF-atoms (Eg. "Cr1" and "Cr2".
   2. Run init_lapw. nn and/or sgroup determines equivalent atoms. Accept eventually the new struct_nn file (You may have to use the same procedure as described in faq:supercells).
   3. Edit case.inst and flip the spin of the second AF atom. This means you must invert the spin-up and dn occupation of this atom. Atoms which carry no spin (e.g. an O between two AF metal atoms) should be made non-spinpolarized by setting equal numbers of up and dn-electrons.
      For AFM NiO case.inst looks like:

      Ni
      Ar 3 5
      3, 2,2.0  N
      3, 2,2.0  N
      3,-3,3.0  N
      3,-3,1.0  N
      4,-1,1.0  N
      4,-1,1.0  N
      Ni
      Ar 3 5
      3, 2,2.0  N
      3, 2,2.0  N
      3,-3,1.0  N   <=== spin flipped
      3,-3,3.0  N   <=== spin flipped
      4,-1,1.0  N
      4,-1,1.0  N
      O
      He 3 5
      2,-1,1.0  N
      2,-1,1.0  N
      2, 1,1.0  N
      2, 1,1.0  N
      2,-2,1.0  N  <=== equal occup for up/dn
      2,-2,1.0  N  <=== equal occup for up/dn
      ****     End of Input
      ****     End of Input

      This case.inst file can also be prepared by the new: instgen_lapw -ask , where you can specify for each atom spin-up, dn or non-magnetic configurations.
   4. Continue with init_lapw (rerunning lstart) and select "spin-polarized" calculations.
   5. You may now run an scf cycle using runsp_lapw; or
   6. You may try to select "AFM-calculations", generate "case.inclmcopy" and use "runafm_lapw". For simplest use of "afminput" you should provide the nonmagnetic (or ferromagnetic) supergroup in "case.struct_supergroup". Please read the usersguide for more details. (help_lapw and search for AFM).

      If you succeed to generate proper input files, you can do the scf-cycle by "runafm_lapw", which will save at least half the computer time, since only one spin-direction is calculated and the other one is generated by symmetry. However, since these programs are little tested, I recommend to check the final results of "runafm_lapw" by
   7. "runsp_lapw". If the charge distance (grep IS case.scf) remains small and the magnetic moments do not change, runafm_lapw was successful, otherwise continue with runsp_lapw until convergence.

      Peter Blaha,

[ Last edited by snowmami on 2010-12-8 at 21:59 ]
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sunyang1988(金币+3):辛苦了 2010-12-11 19:23:30
进行反铁磁计算的步骤:
1、创建一个AF需要的单胞。例如:对于体心Cr,应该选取晶格对称性P(取消对称性),2个不等价原子位置(0,0,0)和(0.5,0.5,0.5).为了使nn选取合适,应该给两个AF原子不同的标记(例如:Cr1&Cr2)
2、运行init_lapw。nn或者sgroup需要等价原子,接受新结构文件struct_nn
3、编辑case.inst并且翻转第二个AF原子自旋。这意味着翻转这个原子占据态的上下自旋。对于不带自旋的原子(例如O原子),应该使用非自旋极化(上下自旋电子数相等)。
对于AFM的NIO 的case,inst为:略
***这个case.inst文件也可以用instgen_lapw -ask命令产生,这个命令可以标记任何原子为上自旋,下自旋,或者非磁。(我在计算AFM时都是使用这个命令)
4、继续init_lapw并且选择自旋极化计算,完成初始化。
5、初始化完成后运行runsp_lapw或者进行第6操作
6、选择AFM-calculations,生成case.inclmcopy文件,使用runafm_lapw。对于afminput最简单的使用,你应该用case.struct_supergroup提供非磁或铁磁supergroup。详细阅读userguide(help_lapw and search for AFM)
成功生成输入文件后,可以运行自恰循环通过runafm_lapw。因为只计算上自旋,其他自旋方向的计算都是通过对称性完成的,所以可以减少一般的计算时间。
7、如果charge distance 仍然很小,磁矩没有改变,运行runsp_lapw,再runafm_lapw。如果还不成功继续runsp_lapw直到收敛。
2楼2010-12-11 19:15:56
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snowmami

新虫 (正式写手)


引用回帖:
Originally posted by gzqdyouxia at 2010-12-11 19:15:56:
进行反铁磁计算的步骤:
1、创建一个AF需要的单胞。例如:对于体心Cr,应该选取晶格对称性P(取消对称性),2个不等价原子位置(0,0,0)和(0.5,0.5,0.5).为了使nn选取合适,应该给两个AF原子不同的标记(例如:Cr1 ...

也许是我太笨了点,还是不懂啊!
您能否结合ZnO的2*2*2超胞中一个Zn原子被Ni原子取代这个体系,具体说一说如何进行AFM的计算呢?特别是那个自动生成*.inst的命令?诸如此类的命令去哪里查找?计算态密度时需要编辑*.int 文件是否也有这么好用的命令呢?呵呵,I'm only a layman on WIEN2k,please tell me in detail. Thank you very much!
3楼2010-12-12 14:26:05
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