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FEFF | 谱学多重散射计算软件

FEFF是一个自洽的多重散射从头计算XAS谱和电子结构的软件包。用于X射线吸收精细结构(XAFS),X射线吸收近边结构(XANES)和原子簇的各种其他光谱的从头多次散射计算。该代码产生许多现代XAFS分析代码中使用的散射振幅和相位,以及各种其他属性。


FEFF 9:最新版本是FEFF9(版本9.6)

FEFF 9具有各种新功能和选项。首先有几个可以用FEFF 9计算的新的光谱,包括电子能量损失谱(EELS)和非共振非弹性X射线散射(NRIXS)。另外,还有各种改进。这些包括; 

(1)从头开始的 Debye-Waller因子;

(2)改善非弹性损失的治疗; 

(3)核心 - 空穴相互作用的改进处理; 

(4)用格林函数的k空间计算更精确地处理结晶体系。  

(5)利用基于自洽的球型MT散射势的实空间Green函数方法, 计算中考虑了polarization dependence, core-hole efects,and local field corrections,et al.

(6)FEFF9增加了倒空间计算(周期边界条件)


FEFF9附带JFEFF GUI。


FEFF能够提供如下的计算:

- 散射振幅: effective scattering amplitude;x-rayelastic scattering amplitude f = f0+f’+if ’’, including Thomson and anomalous parts

- 相移函数 : Ø,effective scattering phase shift

- 平均自由程 : λ,mean free path

- 初始路径长:R0

- Deybe-Waller因子: σ

- feffnnnn:

- chi :

- …..


FEFF9的模块结构


  • 输入、输出处理

  • 原子势计算

  • 嵌入的原子势计算

  • 屏蔽效应计算

  • ldos计算

  • 截面和相移函数计算

  • 全多重散射计算

  • 求GT的迹

  • 路径计算

  • 计算散射振幅和其它XAFS参数

  • 计算指定的谱

  • 计算多电子激发

  • 计算eels



FEFF 8:

FEFF 8 通过包括自我一致的电势计算来提供电荷转移和更精确的费米能级估计,改进了FEFF的先前版本。它还包括完全多次散射计算,以改善XANES计算,其中多次散射扩展可能无法收敛。FEFF 8可输出角动量投影状态密度,x射线发射光谱和x射线散射振幅。FEFF 8.40的改进简化了依赖于自旋的计算,并且可以包括对核心孔和局部场效应的改进处理。FEFF8现在包括JEFEFF,FEFF 8.4的图形前端。 


FEFF is an automated program for ab initio multiple scattering calculations of X-ray Absorption Fine Structure (XAFS), X-ray Absorption Near-Edge Structure (XANES) and various other spectra for clusters of atoms. The code yields scattering amplitudes and phases used in many modern XAFS analysis codes, as well as various other properties.


FEFF 9: The newest version is FEFF9 (Version 9.6)

FEFF 9 has a variety of new features and options. First there are several new spectroscopies which can be calculated with FEFF 9, including electron energy loss spectra (EELS) and non-resonant inelastic x-ray scattering (NRIXS). In addition, there are a variety of improvements. These include; (1) ab initio Debye-Waller factors; (2) improved treatment of inelastic losses; (3) an improved treatment of the core-hole interaction; and (4) more accurate treatment of crystalline systems with k-space calculation of the Green's function.  FEFF9 comes with the JFEFF GUI.


FEFF 8: 

FEFF 8 improves over previous versions of FEFF by including self consistent calculation of potentials to provide charge transfer and a more accurate estimate of the Fermi level. It also includes full multiple scattering calculations to improve XANES calculations, where multiple scattering expansions can fail to converge. FEFF 8 can output the angular momentum projected density of states, x-ray emission spectra and x-ray scattering amplitudes. The improvements in FEFF 8.40 simplify spin-dependent calculations and can include improved treatment of core-hole and local field effects. FEFF8 now includes JFEFF, a graphical front-end for FEFF 8.4. 


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