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xirainbow

木虫 (正式写手)

[资源] 【原创】Partial charge density(for any band at any k point)

以下内容来自我的博客：http://blog.sina.com.cn/s/blog_5f15ead20100d3wp.html

Partial charge density计算或称为Band decomposed charge density计算，即计算特定的某个(或某些)k点和本征值(这些k点和本征值是相互对应的)所对应的本征波函数的平方(也就是电荷密度)。特别是用在 STM的计算中，以及分析特定能量范围内或能量点的化学键特征(或atomic characteristic)。
Ref：http://old.blog.edu.cn/user1/11542/archives/2005/1013029.shtml

以下共给出三个例子加以说明：

Example 1:

  &INPUTPP
                  outdir = '/home/raman/graphene/g55/' ,
                  filplot = '/home/raman/graphene/g55/graphene-psi^2-24band.plot' ,(在pwgui下，必须用绝对路径)
                  plot_num = 7,
                  kpoint = 1,(具体的k点坐标参照.band.out文件)
                     kband = 1,(具体是第几个band参照.band.out文件)

/
&PLOT
                     nfile = 1 ,(代表只有一个输入文件，即INPUTT的输出文件)
               weight(1) = 1.0,(输出数据的权重是1)
                  fileout = '/home/raman/graphene/g55/graphene-psi^2-24band.out' ,
                     iflag = 3 ,
            output_format = 3 ,
                     e1(1) = 10,(画图时，实空间第一个基矢的方向和大小)
                     e2(2) = 0,
                     e3(3) = 0,
                     e2(1) = 0,(画图时，实空间第二个基矢的方向和大小)
                     e2(2) = 10,
                     e2(3) = 0,
                     e3(1) = 0,(画图时，实空间第三个基矢的方向和大小)
                     e3(2) = 0,
                     e3(3) = 10,
                     x0(1) = 0,(画图时，在实空间的起点)
                     x0(2) = 0,
                     x0(3) = 0,
                        nx = 50,(画图时，实空间第一个基矢的方向共分多小个小格)
                        nx = 50,
                        nx = 50,

/
   The code performs two steps:
   (1) reads the output file produced by pw.x, extract and calculate he desired quantity (rho, V, ...)

   (2) writes the desired quantity to file in a suitable format for various types of plotting and various plotting programs.

   The input data of this program are read from standard input or from a file and have the following format:

NAMELIST &INPUTPP
containing the variables for step (1), followed by

NAMELIST &PLOT
containing the variables for step (2)

      The two steps can be performed independently. In order to perform only step (2), leave namelist &inputpp blank. In order to perform only step (1), do not specify namelist &plot

      Intermediate results from step 1 can be saved to disk (see variable "filplot" in &inputpp) and later read in step 2.Since the file with intermediate results is formatted, it can be safely transferred to a different machine. This also allows plotting of a linear combination (for instance, charge differences) by saving two intermediate files and combining them (see variables "weight" and "filepp" in &plot)

Example 2:

&INPUTPP (留白)

/
&PLOT
                     nfile = 1 ,
               filepp(1) = '/home/raman/graphene/g55/graphene-psi^2-24band.plot',
               weight(1) = 1.0,
                  fileout = '/home/raman/graphene/g55/graphene-psi^2-24band.out' ,
                     iflag = 3 ,
            output_format = 5 ,
/

      This example shows how to exacute &INPUTPP and &PLOT independently.

Example 3:

&INPUTPP

/
&PLOT
                     nfile = 2 ,(共两个输入文件)
               filepp(1) = '/home/raman/graphene/g55/graphene-psi^2-24band.plot',
               filepp(2) = '/home/raman/graphene/g55/graphene-psi^2-24band.plot',
               weight(1) = 1.0,(第一个文件的权重)
               weight(2) = -1.0,(第二个文件的权重)
                  fileout = '/home/raman/graphene/g55/graphene-psi^2-24-25band.out' ,
                     iflag = 3 ,
            output_format = 5 ,
/
   This example exhibits how to calculate (psi^2-24 minus psi^2-25). Following this method,I can get 'difference charge density' easily.
   I got the following picture of electronic density from Xcrysden software.

[ Last edited by xirainbow on 2009-8-10 at 15:06 ]

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