Dear Abdul,

Regarding the DFT theory:

DFT, ab initio and semi-imperical such  as AM1 and PM3 are quantum mechanics (QM) methods. 

QM is the correct mathematical description of the behavior of electrons and thus of chemistry. In theory, QM can predict the property of an individual atom or molecule in an exact manner. In practice, the QM equations have only been solved exactly for one electron systems. A myriad collection of methods has been developed for approximating the solution for multiple electron systems.

The quantum mechanics includes: (1) ab-initio, (2)semi-empirical and (3) DFT methods.

 1-      Ab initio Methods:

The term ab initio is Latin for ``from the beginning''. This name is given to computations that are derived directly from theoretical principles with no inclusion of experimental data. This is an approximate quantum mechanical calculation. The approximations made are usually mathematical approximations. Ab initio methods typically are adequate only for small systems and are based entirely on theory from first principles. The ab initio molecular orbital methods (QM) such as HF, G1, G2, G2MP2, MP2 and MP3 are based on rigorous use of the Schrodinger equation with a number of approximations. Ab initio electronic structure methods have the advantage that they can be made to converge to the exact solution, when all approximations are sufficiently small in magnitude and when the finite set of basic functions tends toward the limit of a complete set. The convergence is usually not monotonic, and sometimes the smallest calculation gives the best result for some properties. The disadvantage of ab- initio methods is their enormous computational cost. They take a significant amount of computer time, memory, and disk space.

 2-      Semi-empirical Methods:

 Semi-empirical calculations are set up with the same general structure as a Hartree-Fock (HF) calculation in that they have a Hamiltonian and a wave function. Within this framework, certain pieces of information are approximated or completely omitted. Usually, the core electrons are not included in the calculation and only a minimal basis set is used. Also, some of the two-electron integrals are omitted. In order to correct for the errors introduced by omitting part of the calculation, the method is parameterized. Parameters to estimate the omitted values are obtained by setting the results to experimental data or ab initio calculations. Often, these parameters replace some of the integrals that are excluded.

The advantage of the semi empirical calculations is that they are much faster than ab initio calculations and their disadvantage is that the results can be erratic and fewer properties can be predicted reliably. If the molecule being computed is similar to molecules in the database used to parameterize the method, then the results may be very good. If the molecule being computed is significantly different from anything in the parameterization set, the answers (solutions) may be very poor[1].

The commonly used semi-empirical methods are MINDO, MNDO, MINDO/3, AM1, PM3 and SAM1. Calculations of molecules containing up to100 atoms (this number can be increased if super computers are utilized) can be handled using semi-empirical methods[9, 10].

 3-      Density functional theory (DFT):

             DFT has become very popular in recent years. This is justified based on the pragmatic observation that it is less computationally intensive than other methods with similar accuracy. This theory has been developed more recently than other ab initio methods to investigate the electronic structure (principally the ground state) of many-body systems, in particular atoms, molecules, and molecules in the condensed phases (solid phase).

With this method the energy of a molecule can be determined from the electron density using functions that is functions of another function. This theory originated with a theorem by Hoe burg and Kohn. The original theorem was applied for the ground-state electronic energy of a molecule. A practical application of this theory was developed by Kohn and Sham who formulated a method similar in structure to the Hartree-Fock method.

The DFT method is adequate for calculating structures and energies for medium-sized systems (30-60 atoms) of biological, pharmaceutical and medicinal interest and is not restricted to the second row of the periodic table.

Although the use of DFT method is significantly increasing some difficulties still encountered when describing intermolecular interactions, especially van deer Waals forces (dispersion); charge transfer excitations; transition states, global potential energy surfaces and some other strongly correlated systems. Incomplete treatment of dispersion can adversely affect the DFT degree of accuracy in the treatment of systems which are dominated by dispersion.

 Reference for DFT, you can read:

Parr, R.G. and W. Yang, Density-functional theory of atoms and molecules. Vol. 16. 1989: Oxford university press.

 Regarding the use of DFT:

You need to use the following programs:

The following programs were exploited in the design calculations:

 Arguslab: For drawing the chemical structures and initial optimization of the structures using UFF and AM1 methods. This program is download free.

Gausian 2009: For running all QM calculations (optimization, frequency, IR and Raman spectra, energies and etc.). This program is NOT free. You should purchase it. It can be uploaded on PC.

 Molden: For viewing Gaussian outputs such as DFT outputs. This program is free download.

There are alternatives for Molden such as Gaussian View and etc.

Regarding the keywords to be used in your DFT calculations:

you should access Gaussian 09 manual which is available on line. you use goog;e search "Gaussian 09 manual".

http://www.gaussian.com/g_ur/g03mantop.htm

Hoping this will be helpful,

Rafik

Dear Abdul,

You cant get better and lucid introduction of DFT than above (Prof. Rafik). It is better to read his answers word by word because, each word encircles the bundle of information. He has also provided you some references please go through definitely these are gonna help you.  

All the best!

It partially depends on how much you want to learn and in what context (periodic or molecular).

I would start with a good introduction book like "Essentials of Computational Chemistry: Theories and Models" by Christopher J. Cramer. You can get playing around with practically running calculations with ORCA (if interested in molecular calculations) or Quantum Espresso (if interested in periodic calculations). These are both free programs.

Dear Abdul,

There are a lot of good resources for learning about DFT, both the theory and the practical aspects. Which one to recommend is of course down to personal taste, and also what your background and interests are. I see from your profile you're a PhD student interested in perovskites, in which case plane-wave-based DFT programs may be the most useful to you. I develop a plane-wave-based program called CASTEP (free to academics) [1], but there are many others including ABINIT and Quantum Espresso (both free) and VASP. The website of these programs are good resources for finding out more about DFT (theory and practice) and most code developers will also have workshops where you can learn a lot about DFT and its practical application, in a short space of time.

There are lots of good textbooks on electronic structure theory, including Chris Cramer's as has already been mentioned, but also "Electronic Structure" by Richard Martin or "Electronic Structure Calculations for Solids and Molecules" by Jorge Kohanoff. A more recent book I've found helpful for teaching is "Atomistic Computer Simulations: A Practical Guide" by Veronika Brazdova and Dave Bowler.

If you'd like to start with something shorter than a full textbook, you could look at one of the many good review articles in the scientific literature. Mike Payne et al's paper "Iterative minimization techniques for ab initio total-energy calculations: molecular dynamics and conjugate gradients" [2] is where I started, though there's a lot more in there than just DFT itself, and of course the field has moved on since then. Kieron Burke's "ABC of DFT" [3] is also a classic, and something in between a comprehensive review and a (free) textbook. For a lighter overview I co-wrote a (free) review of DFT for solid-state applications in a Royal Society journal last year that you might find helpful [4], and that same journal issue has several good reviews of DFT for different applications and from different perspectives.

Hope that helps,

Phil Hasnip

(Castep developer)

[1] http://www.castep.org

[2] M. C. Payne, M. P. Teter, D. C. Allan, T. A. Arias, and J. D. Joannopoulos

Rev. Mod. Phys. 64, 1045 (1992). http://dx.doi.org/10.1103/RevModPhys.64.1045

[3] K. Burke and friends, http://dft.uci.edu/doc/g1.pdf

[4] Philip J. Hasnip, Keith Refson, Matt I. J. Probert, Jonathan R. Yates, Stewart J. Clark and Chris J. Pickard, Phil. Trans. R. Soc. A 372, 20130270 (2014). http://dx.doi.org/10.1098/rsta.2013.0270

It's important to decide the level of "understanding" of how DFT works; if you want to really, REALLY understand it, you're going to have to learn a lot of mathematics. If you just want to know what it can do and what a lot of the alphabet soup stuff means, I'd recommend "A chemist's guide to DFT" by Koch. Also, in terms of doing calculations, I've found the software package "Chemcraft" to be very useful. I've never tried "argslab", so it may be just as good, but Chemcraft makes my life a lot easier. 

Good luck!

Mr. Moyez,

The following two refs are very useful to the topic of computational quantum chemistry, generally. They have balanced between the theoy to each methods, application and in parallel references to the corresponding original sources of information:

1. Computational Molecular Science, P. Schreiner, W. Allen, M. Orozco, P. Willett (Eds.), Vols 1 - 6 (pp. 1 - 3041), Wiley, Chichester, 2014.

2. Encyclopedia of Computational Chemistry, PvR Schleyer, N. Allinger, J. Gasteiger, P. Kollman, H. Schaefer III, P. Schreiner (Eds.), Vols. 1 - 5 (pp. 1 - 3375), Wiley, Chichester, 1998.

A book called Computational Chemistry by Errol Lewars is good for DFT and other methods. 

I think if one starts doing some calculations on simple systems, then he can understand much better about what kind of initial conditions to be taken, how post processing can be done and what parameters are needed to understand the system etc. Good books as suggested by the above people help in a great way, but at the same time there should be some practice

It would be interesting for you to read some introductory text in the field, 20 years ago the book "Electron Theory in Alloy Design" by Sir Alan Cottrell and D. G. Pettifor (Institute of Metals 1993) helped me a lot (it is not up-to-date, but gives a fair description of the main characteristics of the used quantum mechanics methods , written by a metallurgist).

1-Density-Functional Theory of Atoms and Molecules; Robert G. Parr, Weitao Yang, Oxford University Press, (1989).

For a more practical-oriented introduction:

2-A Chemist's Guide to Density Functional Theory; Wolfram Koch, Max C. Holthausen, Wiley-VCH Verlag GmbH, (2001).

first you have to decided which code you want to play with DFT.if you really interested on VASP code then you can start with some youtube lecture and side by side following VASP manual

I have written an excellent tutorial on DFT with input files included:

Tutorial: Setting up and running a DFT calculation using quantum espresso

Here is link:

https://medium.com/@benjaminobi/tutorial-setting-up-and-running-a-dft-calculation-using-quantum-espresso-d7a2428495bd

start with very simple things and then see what actually you need to learn and then follow that direction, solve some simple examples first

Dear @Benjamin obi Tayo, Could send me your excellent tutorial on DFT, I can not open the link, my email address: [email protected], thank you very much.

Hi, the textbook "Exploring Chemistry With Electronic Structure Methods" helped me quite a lot, 'cause it provides a series of step-by-step exercises, progressing in complexity and providing each insight to different concepts in DFT and also TD-DFT. Please notice that it is written specifically for the software Gaussian.

Reading software manuals, and watching online tutorials on utube, you can read this article and its supporting Info:

Article Introducing Quantum Chemistry in Chemical Engineering Curriculum

GAMESS is free. Here is an excellent tutorial for setting up a DFT calculation using GAMESS: https://medium.com/modern-physics/tutorial-on-density-functional-theory-using-gamess-5c3e988f5f01

Thank you everyone for your valuable suggestions.

I have found the utube videos by Chris Cramer to be very useful. Here is a link:

https://www.youtube.com/watch?v=ofyr1GyEZsU

Have a look at one of out Prefessors at UAM:

http://webs.ftmc.uam.es/juancarlos.cuevas/Talks/JC-Cuevas-DFT.pdf

You can follow

http://www.ch.ic.ac.uk/harrison/Teaching/DFT_NATO.pdf

Please read carefully, It will be helpful for understanding Density functional theory (DFT).

You can also read this:

"Density functional theory: Its origins, rise to prominence, and future"

Link: https://journals.aps.org/rmp/pdf/10.1103/RevModPhys.87.897?casa_token=0xFJa0xP0y0AAAAA%3Ac8MYd3yeAwBw95XGa_gOBKLtIDMr08vY_K42WSdnkwS1IH3YVY1Z1y5zJUXQaK0N01Px_zkHmIrpIw

Agreed with @ Rafik Karaman

I would highly recommend a Youtube channel that you can learn the fundamentals of DFT and the concept that you need for DFT calculations.

The link is:

https://bit.ly/2UtvbHE

THERE IS A COURSE AVALIBLE EDX ONLINE COURSE

Ponnam Sateesh i couldnt find the course on EDX , would be very kind of you , if you could send a link

Raheel Hammad Following is course n EDX offered by Purdue University. You can check for their latest enrolment.

https://www.edx.org/course/from-atoms-to-materials-predictive-theory-and-simu

firstly,make sure what do you want to do by it, then, search the video and learn from Youtube channel.also it’s better to learn the literature study by DFT

Basanta Kumar Parida go to youtube, there you will find Prof. M.K.Harbola have a nice course on DFT. You can learn there. For software purpose you can email me directly

http://compmatphys.epotentia.com/

Is a excellent online course by teaching the theory with a very nice hands on using quantum espresso https://www.quantum-espresso.org/

Abdul Moyez Dear Abdul.

In practice, you may try and perform QE examples in the PW package.

I want to introduce useful web-site, https://www.materialssquare.com/

You may get free credits when you signed-up.

Rafik Karaman answer provide a good path to start from as a beginner.

You cab try this: https://www.iitk.ac.in/cce/courses/2019/CompChem/ or any other related programs

Please refer to the outstanding book of DFT for beginners as the following link: Book A Chemist's Guide to Density Functional Theory

Theory: Chemistry books in computation give you a general overview to learn what is the advantage of DFT; or why the technique based on specific approximations was built up.

Simulation: you should install the chemistry software that provides DFT calculations and start calculations; sometimes you need to compare the different techniques.

Check http://newton.ex.ac.uk/research/qsystems/people/coomer/dft_intro.html

Also check https://www.coursera.org/learn/density-functional-theory

Hi Dr Abdul Moyez . See the following good link: http://newton.ex.ac.uk/research/qsystems/people/coomer/dft_intro.html

See also the following useful link: http://www.attaccalite.com/wp-content/uploads/2017/04/pdf_DFT4beginners.pdf

Moreover, see the following very good link: https://myweb.sabanciuniv.edu/nhaghmoradi/density-functional-theory-dft/

The following link is very useful : https://www.imperial.ac.uk/media/imperial-college/research-centres-and-groups/computational-materials-science/teaching/DFT_NATO.pdf

You can try youtube videos first.

You can see these videos

https://www.youtube.com/watch?v=K2eAHGxCsEg&list=PL_g4fDi8qyRo9OHSwhERP3IEMZGHADsun

Overall, learning DFT requires dedication and persistence, but by following these steps and seeking guidance from experts in the field, beginners can gain a solid understanding of this important computational method.

Here are some good resources that beginners can use to learn more about DFT:

Here are some books on DFT that can be useful for beginners: