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Manual Pseudopotentials and orbitals Examples

 

Chapter 3 Quick Start Quide

 

The following files are the central input files of ABACUS. Before executing the program, please make sure these files are in the work directory.


1. INPUT file
The file named INPUT contains the setting parameters used in the calculation, which informs the program “what to do and how to do it”. Most parameters are supplied with default values, but some important parameters must be explicitly set by the user. For a complete list of the input parameters, please consult the Appendix 5.1 ‘List of keywords’.
Attention: Users cannot change the filename “INPUT” to other names.

 

2. Structure file, whose default name is STRU.

This can however be changed to a different name by explicitly specifying the name in the INPUT file. As its name indicates, the STRU file contains the structural information about the system, e.g., lattice constant, lattice vectors, and positions of the atoms within a unit cell. The positions can be given either in direct or Cartesian coordinates. Moreover, the name (and location of the pseudopotential and numerical orbital files, see below) need to be specified in the STRU file.


3. The k-point file, whose default name is KPT.
The KPT file contains the information of the k-grid setting for the Brillouin zone sampling.


4. The pseudopotential files.
Norm-conserving pseudopotentials are used in ABACUS, in the UPF file format. The filename (and sometimes location) of each element’s pseudopotential needs to be specified in the STRU file.


5. The numerical orbital file.
When doing calculations with atomic orbital basis, it’s necessary to prepare a numerical orbital file for each element in the system. Generally, the numerical orbital file should be prepared by the user, which will be described later. The filename (and sometimes location) of each element’s numerical orbital needs to be specified in the STRU file.

 

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