24小时热门版块排行榜

返回列表

当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖

cenwanglai

荣誉版主 (知名作家)

[交流] n型掺杂Fe2O3的电子输运性质（Nano Letter, 2011）：embedded cluster + ECPs

这篇文章的技术难点在哪里？新颖性在哪里？计算软件是NWChem+Gamess (谢谢souledge的提醒). 文中有以下几处我不明白：
(1) 下面Figure 1中两个Cluster,为什么左边带15个负电荷，右边有21个负电荷？Figure 1的caption说没有显示capping ECPs和point charge arrays.那么如果把这两项内容显示出来，会是个什么情况？
(2) capping aluminum effective core potentials (ECPs)是什么？文中说这两个clusters中，capping aluminum effective core potentials are used to replace Fe(III) cations that would have been bonded to the terminating oxygen anions.Use of such ECPs prevents electron density on the oxygen anions from artificially drifting outward, by providing effective Pauling repulsion at nearest neighbor cation sites. Al ECPs are used because they have similar ionic radii to Fe(III) cations.为什么这里可以用Al的ECP来取代Fe(III)离子？这段话在说什么？
(3)文中公式（3）下面一段话中说“The clusters with capping ECPs are embedded in a large point charge array meant to represent the extended ionic crystal, where charges of +3 and -2 represent Fe and O ions in the bulk, repectively, and the charges of ions on the edges or surfaces are determined through Evjen's method. The clusters and point charge arrays are built from the experimental crystal structure.”似乎给出了构建模型的重要信息，特别是点电荷阵列，说是根据实验的晶体结构建立的。这段话在说什么？怎么样根据这样的信息来建立这样的模型？
(4)NWChem也是可以计算CASSCF,为什么这篇文章的作者要用Gamess算CASSCF呢？

@zhangguangping
@valenhou001
@yjcmwgk
@aylayl08

[ Last edited by cenwanglai on 2012-8-25 at 14:16 ]

回复此楼

» 本帖附件资源列表

欢迎监督和反馈：小木虫仅提供交流平台，不对该内容负责。
本内容由用户自主发布，如果其内容涉及到知识产权问题，其责任在于用户本人，如对版权有异议，请联系邮箱：xiaomuchong@tal.com
附件 1 : nl200356n.pdf

2012-08-20 22:18:32, 1.69 M

» 抢金币啦！回帖就可以得到:

查看全部散金贴

1楼 2012-08-20 22:19:36

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

cenwanglai

荣誉版主 (知名作家)

cenwanglai: 回帖置顶 2012-08-22 10:06:12

查了几篇文献，了解到：

（1）embedded cluster model,或者称为emdedded approach,the main philosopy behind it as applied to a perfect solid is that a solid can be seen as a central unit cell embedded in the field created by the rest of the unit cells which are identical to the central unit cell except for the fact that they are spatially separated from it by multiples of the unit vectors of the crystal.示意图键图1.
（2）effective core potential (ECP)类似于原子的赝势模型，但是是不同的方法。在处理HF计算的时候，为了加速多电子体系的计算，把内部不参与成键的电子作为核芯势的一种数值处理方法。差别在哪里，我看不懂。NWChem主页上有这样的表述Effective core potentials (ECPs) are a useful means of replacing the core electrons in a calculation with an effective potential, thereby eliminating the need for the core basis functions, which usually require a large set of Gaussians to describe them.

cluster model scheme

[ Last edited by cenwanglai on 2012-8-22 at 10:23 ]

赞一下

回复此楼

11楼2012-08-22 10:00:23

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖

查看全部 13 个回答

souledge

专家顾问 (著名写手)

★ ★ ★ ★ ★ ★ ★
小木虫: 金币+0.5, 给个红包，谢谢回帖
cenwanglai: 金币+5, 谢谢回复~。这家伙还会用vasp. 2012-08-20 23:46:20
xueht987: 金币+1, 鼓励交流 2012-08-21 09:12:34

引用回帖:

The NWChem program [50] is used for all UHF calcula-
tions. CASSCF calculations are performed with the GAMESS
package. [51]

有交代啊～其中NWChem可是算分子之类的好手，记得能够进行MP2，CCSD(T)的计算的～
顺便，看那结构图的原子光线，就不像是与VASP经常搭配的p4vasp或者VESTA那样的单光源软件～色彩风格上比较像V_Sim～

[ Last edited by souledge on 2012-8-20 at 23:19 ]

赞一下

回复此楼

2楼2012-08-20 23:18:05

已阅回复此楼关注TA 给TA发消息送TA红花 TA的回帖