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identation

金虫 (著名写手)

[交流] 【求助】请教siesta可否计算磁性体系的介电极化呢?

It has to be stressed that the macroscopic polarization can only be meaningfully calculated
using this approach for insulators. Therefore, the presence of an energy gap is necessary,
and no band can cross the Fermi level. The program performs a simple check of this
condition, just by counting the electrons in the unit cell ( the number must be even for
a non-magnetic system, and the total spin polarization must have an integer value for
spin polarized systems), however is the responsability of the user to check that the system
under study is actually an insulator (for both spin components if spin polarized).

这段话,请教siesta可不可以计算考虑自旋的介电极化呢?
做的是磁性材料的介电性能计算,要考虑自旋,pwscf没法计算自旋体系的电极化,因为磁性体系一般要用smearing和nbnd多于电子数的一半。
因此想问一下siesta可不可以实现这个功能。,
以上英文是从手册上找到的,但不敢确认,想请教大家一下!
另外,可否发一下siesta计算多铁性材料的例子?
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linghuntuzi

金虫 (著名写手)


identation(金币+2):谢谢参与
本人认为可以,不过也不确定
交流无止境
2楼2010-09-26 08:14:46
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zhangguangping

木虫 (著名写手)

★ ★ ★ ★ ★
identation(金币+2):谢谢参与
aylayl08(金币+2):感谢提供信息 2010-10-21 14:58:30
zzy870720z(金币+2):谢谢转载 2010-10-23 14:24:09
引用回帖:
Originally posted by identation at 2010-09-25 16:53:42:
It has to be stressed that the macroscopic polarization can only be meaningfully calculated
using this approach for insulators. Therefore, the presence of an energy gap is necessary,
and no band  ...

这个是我从一个blog上看到的,不知道对你有没有用。网址:http://blog.chinaunix.net/u2/85704/showart_2022856.html
========================================
Regarding real part of dielectric function



Regarding real part of dielectric function
Systemlabel.EPSIMG  generated by SIESTA, contains the imaginary part of the dielectric function in the energy range specified in the input file of SIESTA. the program The programs contained in the directory (siesta-2.0/Util/Optical) calculate different optical properties of a solid out of the file.

There are two small programs:

input.f

and

optical.f


Both can be compile independently:

     f77( f95, f90,....) input.f -o inpu
     
     f77( f95, f90,....)  optical.f -o optical


* The first program creates the input file for optical (e2.dat), containing the
imaginary part of the dielectric function, from the file Systemlabel.EPSIMG

* The second reads a file called 'e2.dat' containing
the imaginary part of the dieletric function, and creates the
files :
'epsilon_real.out'  containing the real part of the dielectric function
'epsilon_img.out'  containing the imaginary part of the dielectric function
'refrac_index.out'   containing the refraction index
'absorp_index.out'  containing the extintion coefficient
'absorp_coef.out'    containing the absorption coefficient in cm**-1
'reflectance.out'     containing the reflectance
'conductivity.out'     containing the optical conductivity in (ohm*m)**-1

To do so, you just need to type:

    ./ input < Systemlabel.EPSIMG
  
    ./optical
Karim
=========================================
弘德明志博学笃行
3楼2010-10-21 14:55:11
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