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obco有什么区别,科学网-COHP-初探:为了忘却的纪念vs wxDragon数据处理

互联网 2020-11-29 03:10:50

关注:

1) COHP原理、参数设置、运行过程中警告warning及其对结果影响分析

2)  extended Hückel method   与http://yaehmop.sourceforge.net/

3)     mulitwfn   http://multiwfn.codeplex.com/

COHP/COOP原理、解薛定谔方程时,有正的重叠积分表示成键态,反的表示反键态。

  两种元素的PDOS有重叠,表明这两种元素之间有成键作用。共价、离子及金属键作用如何看出?

Finally, the COOP indicator results from multiplying the DOS by the overlap population (hence its name), and it adds an additional dimension—the precious bonding information:

    COOP adopts positive values (bonding, because of the positive overlap population) in the lower region of the band, and negative values (which identify antibonding interactions) at higher energy levels. By comparing the band structure and its orbital icons with the COOP diagram, it is obvious why the nearest-neighbor COOP is bonding at low energies and antibonding at high energies.

   Welcome to the YAeHMOP home page. This page has been set up to provide online support for the freely available extended Huckel calculation and visualization package YAeHMOP.

Yet Another extended Huckel Molecular Orbital Package (YAeHMOP) was developed by Greg Landrum whilest a graduate student in the research group of Professor Roald Hoffmann at Cornell University. YAeHMOP is intended to be an easy to use, transparent, extended Huckel calculation and visualization package which can perform calculations on both molecular and extended materials in 1,2, or 3 dimensions.

Multiwfn全称为Multifunctional wavefunction analyzer,是由北京科技大学化学与生物工程学院卢天编写的一个十分强大的波函数分析程序,能够实现量子化学领域几乎全部最重要的波函数分析方法[1]。此程序的用户遍及世界各地,目前已被超过两百篇学术论文或书籍所使用

COHP手册解读

运行总结:

1.产生full k-mesh的INCAR应该与静态计算用的INCAR相同,只是静态计算时需注释掉下面的项:

#LSORBIT = .TRUE.;  ISYM=0

2.-pCOHP0,成键区域,费米能级向上(反键区域)移动,材料失稳;反之,材料稳定性增加。

The electronic situation is perfectly optimized and any electronic density hypothetically added would push the Fermi level  inline image up into the antibonding area ( inline image), thereby destabilizing the crystal. It is also convenient that the pCOOP gives qualitatively the same result.

3. 如何对待运行out文件中的splitting参数,越大说明什么问题?

4. _sv、_pv势为什么不能用

5.用Origin重绘图时,需减去费米能级处能量值

6.-pCOHP、COHP、COOP单位问题

INCAR文件如下所示:

PREC = Accurate#LREAL = AutoLREAL = .FALSE.ISMEAR = -5

#LSORBIT = .TRUE.;  ISYM=0

NSW = 0 ; ISIF = 0#NSW = 100 ; ISIF = 3 ; IBRION = 2EDIFF = 1.0d-7EDIFFG = -1.0d-4

NBANDS = 48NPAR = 1

NEDOS = 801LORBIT = 12

必须使两次计算的INCAR一致(尤其是这些参数保持一致),才能产生可归一化的满足计算要求的full k-mesh,如不一致,则会出现如下错误:

1 Getting Started

1.1 Installation

1.2 Preparing your VASP calculation----a static run (no movements of atoms, NSW = 0).

At this time, you should be ready to run your first calculation. Keep in mind that we process plane-wave/PAW output; at the moment, that of VASP. In other words, you need to prepare a VASP wavefunction, and it is absolutely necessary that this is done in a static run (no movements of atoms, NSW = 0). Take care to have the WAVECAR file written to disk (LWAVE = .TRUE.). Remove any previously created WAVECAR file.

1.2.1 INCAR

Ti的INCAR

PREC = Accurate#LREAL = AutoLREAL = .FALSE.I

SMEAR = -5     #important!!!!!!!!!!!!!!!!!!!!!!!

#LSORBIT = .TRUE.; ISYM=0

NSW = 0 ; ISIF = 0#NSW = 100 ; ISIF = 3 ; IBRION = 2EDIFF = 1.0d-7EDIFFG = -1.0d-4

NBANDS = 18    #  2ions+8electrons=10,10/2=5  important!!!!!!!!!!!!!!!!!!!!!!!NPAR = 1   #  important!!!!!!!!!!!!!!!!!!!!!!!

NEDOS = 801LORBIT = 12    #important!!!!!!!!!!!!!!!!!!!!!!!

GaAs的INCAR

PREC = AccurateLREAL = .FALSE.ISMEAR = -5NBANDS = 8      #2ions+(3+5)electrons=10,10/2=5NPAR = 1

NSW = 0 ; ISIF = 0EDIFF = 1.0d-7

NEDOS = 801LORBIT = 12

NBANDS and NPAR=1设置说明

This is an important point, so we have given it a separate section. You need to use as many bands as there are orbitals in your local basis, for simple mathematical reasons. The default setting of VASP is usually lower (and this is fine for all that VASP does!); for a LOBSTER analysis, however, you need to manually set NBANDS in the INCAR file of the final run.

If you run VASP in parallel (NPAR > 1), keep in mind that NBANDS may be automatically adjusted (VASP notifies you about this in its output). To definitely get the number of bands you requested, put the following into the INCAR:NPAR = 1

1.2.2  KPOINTS说明

LOBSTER does not yet deal with k-point symmetry—in other words, your VASP WAVECAR must contain results for the entire mesh, not only the irreducible one usually given in the IBZKPT file.

To get out of trouble, switch off symmetry in the INCAR (ISYM = 0), add LSORBIT = .TRUE. in the INCAR and have the non-collinear version of VASP run for a short time. (This is a cheap trick, admittedly, but it creates a full k-point mesh very conveniently.) The IBZKPT file should now contain all points with equal weight (the last column should contain only 1’s). After a moment, interrupt VASP, remove the LSORBIT line again and do the following:

cp IBZKPT KPOINTS

1.2.3 POTCAR说明

     In the current version, do not use ultrasoft pseudopotentials (“US-PP”) in your POTCAR; please use PAW potentials instead. Also, the gamma-only version of VASP is not supported; please run the single-point calculation with the “default” (complex) version, no matter which k points you are looking at. Finally, we currently recommend avoiding _sv potentials in the single-point calculation.

1.4 Running LOBSTER

~  lobster

2 The lobsterin File2.1 How the input works

LOBSTER is controlled by a single file called lobsterin. This file is designed such that it needs only minimal user input. Usually, the default parameters are fine:

you should only need to set the energetic window, the local basis (e.g., “4s 4p” for gallium, or also “4s 4p 3d”, depending on your plans).

   The lobsterin file also contains those atom pairs for which you intend to do pCOOP/pCOHP analysis.The lobsterin file is not cAsE sEnSiTiVe, and comments may be added using an exclamation mark. (Everything in a line before an exclamation mark, however, will be read and processed!)

! This is an example for the lobster control file lobsterin.! Comments are marked with a !! basisSet koga  ! works up to Lr (Z

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