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FEFF是自洽的多沉散射重新推算XAS谱和电子结构的软件包
。用于同时推算X射线吸收光谱和电子结构
。输出扩大的X射线吸收精密结构（EXAFS），X射线吸收光谱（XAS）的全屡次散射推算以及投影的部门密度（LDOS）
。光谱边缘结构左近的X射线吸收（XANES），X射线天然和磁性圆二色性（XNCD和XMCD），自旋化X射线吸收光谱（SPXAS和SPEXAFS），非共振X射线光谱（XES），X射线散射幅度（Thomson）和电子能量损失谱（EELS）
。该代码产生现代XAFS分析代码中使用的散射振幅和相位，以及属性
。

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FEFF 9：新版本是FEFF9（版本9.6）

FEFF 9 拥有新职能和选项
。有几个能够用FEFF 9推算的新的光谱，电子能量损失谱（EELS）和非共振非弹性X射线散射（NRIXS）
。另表，还有改进
。这些;?

（1）重新起头的 Debye-Waller因子;

（2）非弹性损失的医治;?

（3）主题 - 空穴相互作用的改进处置;?

（4）用格林函数的k空间推算更地处置结晶系统
。??

（5）利用基于自洽的球型MT散射势的实空间Green函数步骤, 推算中思考了polarization?dependence, core-hole efects,and local field corrections,et al.

（6）FEFF9增长了倒空间推算(周期天堑前提)

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FEFF9附带JFEFF GUI
。

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FEFF可能提供如下的推算：

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

- 相移函数: ?，effective scattering phase shift

- 均匀自由程: λ，mean free path

- 初始蹊径长：R0

- Daybed-Waller因子: σ

- feffnnnn:

- chi :

- …..

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FEFF9的？榻峁

• 输入、输出处置

• 原子势推算

• 嵌入的原子势推算

• 屏蔽效应推算

• ldos推算

• 截面和相移函数推算

• 全多沉散射推算

• 求GT的迹

• 蹊径推算

• 推算散射振幅和XAFS参数

• 推算指定的谱

• 推算多电子引发

• 推算eels

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FEFF 8：

FEFF 8 通过自我的电势推算来提供电荷转移和更的费米能级估计，改进了FEFF的版本
。它还屡次散射推算，以XANES推算，其中屡次散射扩大可能无法收敛
。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推算，并且能够对主题孔和部门场效应的改进处置
。FEFF8此刻JEFEFF，FEFF 8.4的图形前端
。?

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【英文介绍】

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.

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FEFF is a software program used in x-ray absorption spectroscopy. It contains self-consistenr real space multiple-scattering code for simultaneous calculations of x-ray-absorption spectra and electronic structure. Output includes extended x-ray-absorption fine structure, full multiple scattering calculations of varioud x -ray absorption spectraand projected local densities of states. The spectra include x-ray absorption near edge structure, x-ray natural circular dichroism, and non-resonant x-ray emission spectra. Calculations of the x-ray scattering amplitude and spin-dependent calculations of x-ray magnetic circular dichroism and spin-polarized x-ray absorption spectra are also possible, but less automated.

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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 that 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 the k-space?calculation of the Green's function.? FEFF9 comes with the JFEFF GUI.

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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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