Frequently Asked Questions¶
When should I use CONQUEST?¶
You can use CONQUEST for any DFT simulations that you need to perform. It is efficient for small problems, though may not be as efficient as other codes (e.g. plane wave codes) because it has been designed for massively parallel operation, which brings some overhead. If you need to perform DFT calculations on large systems (several hundred atoms or beyond) or want to perform highly parallel calculations, you should definitely consider CONQUEST.
When should I use linear scaling?¶
You should use linear scaling if you need to model systems with more than about 5,000 atoms, though gains are often found for smaller systems (from 1,000 atoms upwards).
Linear scaling calculations offer the prospect of scaling to significantly larger systems than traditional DFT calculations; however, they make approximations and require some care and characterisation. In particular, instead of solving for eigenvalues and eigenstates, linear scaling methods solve for the density matrix, so that energy-resolved information (e.g. DOS and band energies) are not available. To enable linear scaling, a range is also imposed on the density matrix and it is important to test the effect of this range.
Will you implement a specific feature for me?¶
We cannot guarantee to implement specific features, though we are always happy to take suggestions. We also welcome new developers: if there is something that you would like to see in the code, please do talk to us about joining the development effort.
How do I report a bug?¶
Please use the GitHub issues page. Include details of the compiler and libraries used, the version of CONQUEST, and the input and output files (if possible). We will do our best to check the bug and fix it, but cannot guarantee to help on any timescale.