s********n
发帖数: 235 | 1 Title: BAND-STRUCTURE AND DENSITY-OF-STATES OF NAXWO3
Author(s): ZHAN, CG; ZHENG, F
Source: THEOCHEM-JOURNAL OF MOLECULAR STRUCTURE Volume: 104 Issue: 1
Pages: 89-98 Published: SEP 1993
apps.webofknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&
qid=2&SID=V2D@HG4lld1gEjiM9eJ&page=8&doc=75
Title: ANDERSON LOCALIZATION IN TUNGSTEN BRONZES - A NUMERICAL STUDY
Author(s): KOSLOWSKI, T; VONNIESSEN, W
Source: PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL
MECHA... 阅读全帖 |
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H*****l
发帖数: 702 | 2 当年IBM把一个ultra high vacuum 的PECVD要送我们实验室
那个设备本来是create来做SiGe/Si phonon的
中国有个企业花300万美元要买
当年AMAT给IBM做都没这么贵
IBM想卖，结果商务部没批准。。。
还放在我们这里落灰。。。。赫赫
从送来就没开过封。。。
一般的MOCVD早就烂大街
你现在回国说要做solar cell,不做CIGS，3-5 or Nitride都不好意思和人打招呼
我们这里从国内来的高访，回国以后全部教授不当了，开公司了。。。
国内马上CIGS公司也要满地都是了。。 |
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i*******e
发帖数: 27 | 3 band structure, phonons, transport equations for charges and mechanisms of
generation and recombination of carriers. Study of establishment of physical
and phenomenological models for three basic features of the electronics:
the PN junction, the bipolar transistor and MOS transistor.
就这个方面的 谢谢 d****[email protected] |
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H*****l
发帖数: 702 | 4 在Gatech跟Cressler做SiGe肯定有前途阿
SiGe在半导体工业还是很无敌的
但是看lz作什么了
用什么SiGe做phonon generator就是扯淡了 |
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a***u
发帖数: 9 | 5
hole
is
The question you asked is so complicated that very few people really know the
answer. Since I am not working on polymer transistor, I know no more than you
do. First of all, how do we define intrinsic mobility? For inorganic
semiconductor, it is quite simple. Because people can make high quality single
crystal. So we can really study how the mobility is dependent on temperature
and impurity level (phonon scattering and impurity scattering). On the other
hand, polymer is polycrystalline |
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m******i
发帖数: 834 | 6 Nanocrystalline Nanowires: I. Structure
Philip B. Allen
Nano Lett.; 2007; 7(1) pp 6 - 10; (Letter) DOI: 10.1021/nl062139z
Geometric constructions of possible atomic arrangements are suggestedfor
inorganic nanowires. These are fragments of bulk crystals, andcan be called
"nanocrystalline" nanowires (NCNW). To minimize surfacepolarity, nearly one-
dimensional formula units, oriented along thegrowth axis, generate NCNWs by
translation and rotation.[float=left]
Nanocrystalline Nanowires: 2. Phonons |
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w********h
发帖数: 12367 | 7 Raman-allowed phonon high-frequency first-order mode |
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F**D
发帖数: 6472 | 8 absorption = heat+ other phonons |
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f*******n
发帖数: 27 | 9 We are inviting applications for funded PhD student positions at the School
of Mechanical Engineering, Purdue University. Applicants with Bachelor or
Master Degree in one of the following disciplines: physics and applied
physics, mechanical engineering, electrical engineering, and materials
science, and with interests in one of the following areas: optics, heat
transfer, NEMS/MEMS, metrology, photonics and phononics, and magnetics, are
strongly encouraged to apply. The position will start from S... 阅读全帖 |
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B****p
发帖数: 18 | 11 简单地讲，fermi golden rule 应用到固体（就晶体吧）上，主要是要计算激发态的态
密度 (density of states）。 这是一个多体问题。
现有的计算方法有一些，如基于平均场DFT的能带理论（包括DSFT, DFT+U, TDDFT)，基
于格林函数的GW法，基于CONFIGURATION INTERACTION的cluster model。。。用什么方
法，主要看你想解决什么样的问题。
另外，固体的元激发有很多，不知道你具体想了解那种？ i.e. phonon, plasmon,
core electron, Compton, exciton...
我觉得你的题目其实和你问的内容关系不大。光和物质的作用包涵激发态的研究（如x-
ray，电子的非弹性散射），但他的内容要广的多。
激发态，你可以看一下入门书“Unoccupied Electronic States: Fundamentals for
Xanes, Eels, Ips and Bis (Topics in Applied Physics) by J. C. Fuggle (Author
), J. |
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d********1
发帖数: 73 | 12 dddttt4321:“边缘物理”，具体讲是材料物理（optical generation and
characterization of acoustic phonons in nanomaterials）和生物物理（蛋白质在
nanofluidics中的结晶）. |
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d********1
发帖数: 73 | 13 dddttt4321:“边缘物理”，具体讲是材料物理（optical generation and
characterization of acoustic phonons in nanomaterials）和生物物理（蛋白质在
nanofluidics中的结晶）. |
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a*****e
发帖数: 4577 | 14 好像F_1u是IR active的
但是这个F_1u是指的光学声子吗？
对于砷化镓来说
BTW, GaAs是金刚石结构 |
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a*******r
发帖数: 7558 | 15
GaAs是闪锌矿结构, 不里渊中心点有一个三重简并的F2模，
既是raman也是IR活性。 |
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a*****e
发帖数: 4577 | 17 当然，可以认为能量本身的定义无所谓
现在回到我最初的那个问题，
用分子动力学算出的系统动能，和体系实际温度之间的关系到底是怎么样的？
如果不知道phonon density of states, 怎么能得到实际温度和molecular dynamics
温度的关系
理论上来说两者在高温下应该十分接近
我试过用debye model，似乎在高温下两者并不一样 |
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b*********r
发帖数: 114 | 18 1.作Angle resolved photoemission spectroscopy 实验时，角度反映的出来的是什么
信息？
2.理论计算electron自由能时，用到微扰理论和phonon-electron 作用过程,这个过程
是实际发生的，还是为计算方便虚拟的。因为有些声子过程，声子存在极度短，象不存
在，但计算时必不可少。
feichang xiexie! |
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S*********g
发帖数: 5298 | 19 We don't know what leads to HTSC yet.
But the common wisdom is that it is not phonon. |
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m**n
发帖数: 9010 | 20 前面Superstring同学说了, 我也同意, 现在大部分人相信High Tc不是
mediated by phonons.
既然楼主想问如何用perovskite structure解释高温超导, 那么我只好
给他往这上凑了. |
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a*****e
发帖数: 4577 | 21 对于晶体，为什么只有gamma点的phonon modes对于红外谱比较重要？
按我的理解，因为光子动量小，按照动量守恒定律的要求
如果要和gamma点之外的其他声子作用的话，
整个过程至少需要包括两个以上的声子，因此是一种高阶作用，intensity比较小
不知这种理解是否正确？ |
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g******9
发帖数: 11 | 22 请问超晶格中声子振动(Raman或DECP：Displacive Excitation of Coherent Phonons)
的品质因子（Q factor）怎么计算？
比方说 GaAs/AlGaAS 超晶格中的quality factor。
能大概说一下计算步骤或推荐相关的论文、书籍么？谢谢 |
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a*******i
发帖数: 11664 | 23 I didn't read the paper very carefully but this is about measurements on
nanopariticles with diameters of 10-
12 nm, right?
when you read most textbooks, they say:
for direct bandgap: alfa ~ (hv-Eg)^0.5
for indirect bandgap: alfa ~ (hv-Eg+/-phonon)^2
those two equations are for 3D bulk materials! not for 2D Quantum Well or 1D
nanowire or QDs.
The relation between the absorption coefficient and the energy is mainly
determined by the density of states.
The density of states for 3D, 2D, 1D and QDs |
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f**********r
发帖数: 61 | 24 Glass's band gap is about 9 eV. The energy of visible lights range from 1 eV
to 4 eV and they can not be absorbed by glass. Other materials' band gap
and phonon spectrum are very small and then those lights will be absorbed
in this case. |
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C**R
发帖数: 1047 | 25 no, BCS tells you low Tc SC is due to electron-phonon coupling. Tc of low-Tc SC can be predicted fairly accurately by DFT.
what r u working on? writing proposals? |
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w*******e
发帖数: 83 | 26 Not sure, but looks like phonon energy |
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c**e
发帖数: 236 | 27 谢谢
是不是测量emission随温度的变化
可以看出exciton和phonon的peak变化不同 |
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p*****0
发帖数: 1100 | 28 Why longitudinal phonons cannot be observed in the normal infrared
absorption experiments? |
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a*****e
发帖数: 4577 | 29 在离子晶体里面比如MgO
用什么Potential/XC比较好？
我用的Mg O (ultrasoft) + LDA, 感觉效果不好，算出来的phonon frequency偏低
可不可以认为 离子晶体里面 density gradient 大，因此GGA>LDA? |
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f**********r
发帖数: 61 | 30 算phonon，PAW+GGA的组合比较好。GGA给出的晶格常数接近实验值。
但是LDA给出的电子性质比较准确。原因是GGA用gradient 修正了correlation part,但
是没有修正kinetic part。而LDA什么都不作修正，两个误差反而抵消掉了。所以有些
人喜欢GGA,有些喜欢LDA。 |
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O***e
发帖数: 89 | 31 In liquid, viscosity has the unit of Pa.s, in glasses, there is also
viscosity with a much larger number, but there is also internal friction,
whose unit is Hz to characterize the life time of phonons, some papers
mentioned they are the same thing and I am confused, what is the connection
between them?
In liquid, my boss mentioned Debye model for relaxation time t changing with
temperature,when wt=1, viscosity is the maximum. Anyone know a textbook
about this?
Thanks very much! |
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a********0
发帖数: 34 | 32 Conceptually, viscosity and internal friction is the same thing. But you can
measure it by different means, resulting in different quantities and units.
Viscosity is a measure of stress at a certain strain rate. Glass's viscosity
may be very high but because it can still flow its viscosity is still
finite. You can directly measure viscosity based on its definition.
I don't know much about "phonon lifetime" but I guess you are talking about
some mechanical relaxation test, probably using acoustic... 阅读全帖 |
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m**n
发帖数: 9010 | 33 一般的中子散射测phonon, 在这个能量范围, 误差在1 meV左右很正常.
中子当然是bulk probe.
此外, 具体IR的测量我不清楚, 但大部分这一类靠photon的测量(Raman, ARPES...),
都是surface sensitive的. |
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a*****e
发帖数: 4577 | 34 raman是虚拟态没错啊
但是也是入射光子的能量和出射光子的能量差一个声子的能量
当然和声子有关。
IR是一个低能量的光子子直接被吸收产生声子
最后都是和Phonon有关啊。 |
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a*****e
发帖数: 4577 | 35 就以双原子立方晶体为例，只考虑zone-center
原子a有三个原子b相邻，由于对称性，三个zone-center的声子都是对应相邻原子之间
的相对运动，应该是完全对称的
为什么会有LO和TO的splitting?
黄昆的固体物理书写的很简单
对于横波, \nabla\dot W_t=0,
对于纵波，\nabla\dot W_l\neq 0
但是具体想想这三种振动模式，还是无法理解其区别在哪。
不知道有没有哪位牛人帮忙解释下，谢谢 |
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m**n
发帖数: 9010 | 36 在zone center本来就没有LO和TO的差别.
q <> 0的时候, 才有longitudinal与transverse的概念. |
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s*******i
发帖数: 12823 | 37 长波极限下LO跟TO的能量是一样的啊，都 \sim m/M
你说的splitting是只非长波极限的时候？ |
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s*******i
发帖数: 12823 | 39 这个我没研究了：）
不过黄昆的书里也有提，这个跟离子晶体有关系(P102)
我猜测是因为原子之间的相互作用是库伦势，是长程力
谐振子模型应该得不出这个splitting |
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h*****y
发帖数: 298 | 40 是不连续的，很多材料中沿不同的k方向逼近Gamma点的LO-TO split可以不同。 |
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C**R
发帖数: 1047 | 41 mean free path/fermi velocity |
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E*******1
发帖数: 3464 | 42 Raman Shift就是phonon的能量,因为spectrometer记录了scattered light的能量，E_
incident light- E_scattered light == E_phonon，理论上其实很难，民科的解释很
简单，wiki就行了
一般谱单位都是cm-1，换成THz的话就是乘上光速(3*10^10cm/s) |
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E*******1
发帖数: 3464 | 43 你说你怎么学的，这个出来的当然不是声子的wave number，是前后inelastic light
scattering的能量差，说白了是光子的wave number， 你把能量守恒和动量守恒混成一
个方程了
Raman里面声子的q理论上只能是0啊，因为声子的波数和光子的波数差了好几个量级，
否则为什么1st order raman只能记录gamma点上的信息
不能用光的速度吧？只知道波长，不知道频率，不是还是算不出来能量么
知道有效质量。这个phonon的质量一般怎么取呢？ |
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c******7
发帖数: 439 | 44 起因是老板要去讲个summer school, 觉得输运方向没什么好教材.
我也正想好好学学这个方面, 也许先看看各种相关的书, 做个读书笔记什么的.
然后按照老板的思路把一些经典的砖头里面的东西顺一下.
看能不能搞个讲义似的东西.
我老板做spin Seebeck发了几篇nature.
主要的内容会是温度梯度, 磁场, 电场下固体的输运性质
Seebeck effect, Nernst, 以及磁阻这样的二阶效应
各种Onsager关系
主要会参考
Harman, T C, and J M. Honig.
Thermoelectric and Thermomagnetic Effects and Applications. McGraw-Hill,
1967.
Ziman的electrons and phonons.
Wilson的the theory of metals.
Putley, E. H. The Hall Effect and Semi-conductor Physics. Dover Publications
, 1968.
然后往里面加自旋, spin-Seebeck... 阅读全帖 |
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y******u
发帖数: 141 | 45 【 以下文字转载自 Immigration 讨论区 】
发信人: yshanwvu (单眼皮), 信区: Immigration
标 题: 出邪招，求引用 (物理）
发信站: BBS 未名空间站 (Fri Jan 11 10:48:37 2013, 美东)
物理的引用太少了。
三年了，才80不到。 不蛋定了，出邪招， 求引用。 嘿嘿嘿
关键词： Raman, CARS, EPR, TiO2, KTP, OPO, point defects, Non-linear optical
imaging,
同时，作为AIP， OSA， APS， SPIE, elsevier 的审稿人， 兼求审稿。
想年底把EB1-A 交出去，憋不住了。
14. “Ultrafast decay of high frequency optical phonon mode in KTiOPO4,”
Appl. Phys. Lett. 99, 221903 (2011).
13. “3D nonlinear microspectroscopy and imaging of soft condensed ma... 阅读全帖 |
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s********k
发帖数: 107 | 46 热传导还有phonon。虽然比不过电子，但随温度同样是代数衰减。
100meV |
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m**o
发帖数: 9805 | 47 it's useless if pumping is needed
plus this is local measurement, which can hardly be considered true sc.
room temperature "sc gap" has been reported long time ago by stm LDoS
measurement, but you can never get transport sc
it only indicates some sort of cooper pair correlation. given the energy
scale of the pumped phonons, it's possible, but nothing deeper. it has
nothing to do with true high Tc sc. (the measurement is along c-axis). |
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m**o
发帖数: 9805 | 48 it's useless if pumping is needed
plus this is local measurement, which can hardly be considered true sc.
room temperature "sc gap" has been reported long time ago by stm LDoS
measurement, but you can never get transport sc
it only indicates some sort of cooper pair correlation. given the energy
scale of the pumped phonons, it's possible, but nothing deeper. it has
nothing to do with true high Tc sc. (the measurement is along c-axis). |
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E*******1
发帖数: 3464 | 49 背景是实验和计算一半一半，做材料里phonon dynamics的，属于小community。文章有
3，4篇通讯作者加一作的都发在PR上，所以审过几次PR的文章，再无其他。凝聚态的杂
志无比的多，但是悲剧的是从来没人找我做审稿的，难道非要很有名发一堆文章才能入
editor的法眼？而且大多数杂志好像也没有reviewer的注册登记页面，不知道怎么才能
多几个杂志来混审稿人当当，望众大神指教 |
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E*******1
发帖数: 3464 | 50 背景是实验和计算一半一半，做材料里phonon dynamics的，属于小community。文章有
3，4篇通讯作者加一作的都发在PR上，所以审过几次PR的文章，再无其他。凝聚态的杂
志无比的多，但是悲剧的是从来没人找我做审稿的，难道非要很有名发一堆文章才能入
editor的法眼？而且大多数杂志好像也没有reviewer的注册登记页面，不知道怎么才能
多几个杂志来混审稿人当当，望众大神指教 |
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