Problem in convergence in Quantum espresso

In summary: Additionally, if the system you are trying to model is inherently complicated – for example, if it involves multiple electronic states or a large number of atoms – it can be difficult to converge the calculation without very careful treatment. In summary, the speaker is experiencing difficulties with the SCF calculations for their constructed slab of rutile TiO2 (110) with 11 Angstroms vacuum, and is seeking suggestions to improve the convergence. Possible issues could include not enough iterations or overly strict convergence criteria, but there may also be more complex problems with the system itself.
  • #1
Arun Prasath
15
0
I have constructed mono layer slab of rutile TiO2 (110) with 11 Angstroms vacuum between two layers. I used the Quantum wise software for the construction of the slab. Then I have exported the Quantum espresso input from Quantum wise software. Now the problem is the SCF calculations are not converging upto 500 iterations. Do I need to increase the number of iterations? If that so what is the maximum possible number of iterations ? Or else what is the problem in converging? Friends Your suggestions will be valuable for my calculations. Thank You in advance.
 
Physics news on Phys.org
  • #2
This is a tough question to answer without knowing more. SCF calculations will sometimes fail to converge because you haven’t given them enough iterations; however, 500 should be plenty. Another cause is that the convergence criteria are to tight. The program signals convergence when the change between iterations falls below some threshold parameter that’s usually adjustable. If this parameter is set too low, the program can have trouble reaching convergence within the number of iterations.

There are also more physically motivated problems that can prevent calculations from converging. For example, most ab initio programs require some sort of initial guess for the electronic state. If this guess is totally off-base, the calculation can have trouble converging.
 

Related to Problem in convergence in Quantum espresso

1. What is the problem of convergence in Quantum espresso?

The problem of convergence in Quantum espresso refers to the difficulty in reaching a stable and accurate solution for a given quantum mechanical system. In other words, the calculations may not converge to a consistent and reliable result, making it challenging to accurately predict the behavior of the system.

2. What causes the problem of convergence in Quantum espresso?

There can be several reasons for the convergence problem in Quantum espresso, such as insufficient number of iterations, inappropriate choice of basis set or pseudopotentials, and complex electronic structures of the system. In some cases, it can also be caused by technical issues, such as insufficient memory or computing resources.

3. How can the problem of convergence in Quantum espresso be solved?

There is no universal solution for the convergence problem in Quantum espresso, as it depends on the specific system being studied. However, there are several techniques that can be used to improve convergence, such as increasing the number of iterations, changing the basis set or pseudopotentials, and optimizing the electronic structure. It may also help to consult the Quantum espresso community for advice and troubleshooting.

4. Can the problem of convergence in Quantum espresso be avoided?

In most cases, it is not possible to completely avoid the convergence problem in Quantum espresso. However, proper selection of parameters and settings, as well as careful analysis of the system, can significantly reduce the chances of encountering this issue. It is also essential to regularly monitor and validate the convergence of calculations to ensure reliable results.

5. Is the problem of convergence in Quantum espresso common?

The problem of convergence is a common issue in quantum mechanical calculations, including those performed in Quantum espresso. However, the frequency of encountering this problem can vary depending on the complexity of the system and the expertise of the user. With proper understanding and experience, it is possible to minimize the occurrence of convergence issues in Quantum espresso.

Similar threads

BURAI quantum espresso GUI error
    • Computing and Technology
Replies
2
Views
2K
A Quantum Espresso Tutorial: h-Boron Phosphide Variable-Cell Relaxation
    • Atomic and Condensed Matter
Replies
1
Views
2K
Doping Rutile TiO2 with Quantum ESPRESSO v5.0.1
    • Atomic and Condensed Matter
Replies
1
Views
4K
I Two recent tests of loop quantum gravity theory
    • Beyond the Standard Models
Replies
9
Views
658
A The eigenvalue power method for quantum problems
    • Quantum Physics
Replies
2
Views
1K
Recent papers on self-dual loop quantum black holes
    • Beyond the Standard Models
Replies
28
Views
4K
Programs How good is this applied math program?
    • STEM Academic Advising
Replies
13
Views
2K
Are Women and New Researchers Shaping the Future of Quantum Gravity Studies?
    • Beyond the Standard Models
Replies
24
Views
7K
Quantum cosmo test prospects (sampling the literature)
    • Cosmology
Replies
5
Views
3K
Why do degenerate energy levels shift or split due to perturbation?
    • Advanced Physics Homework Help
Replies
6
Views
3K

Hot Threads

Recent Insights

Back
Top