How to create input files?¶
Input-file preparation dialogue box creates files in the order of Structure–>K-points–>Potential–>Instructions, which in the case of VASP translates to the order POSCAR–>KPOINTs–>POTCAR–>INCAR.
CINEMAS can create a structure file from the scratch by taking symmetry and site information, or load structure files from several formats such as .xsf(XCrysden), .vasp(VASP), .in(Quantum Espresso), .cif and etc. Generation of a structure from the scratch is performed using spglib, while cif format is handled using pymatgen libraries.
Once symmetry/site data or a file-form-disk is exported, further atomic sites can be added or deleted or degree-of-freedom for structural relaxation can be restricted(the same can be done from structure manager side as well).
From the second tab, K-points file can be created in two modes: either in automatic or band-structure mode. Automatic mode is self-explanatory, while for the band-structure mode, using icon Brillouin zone for any loaded structure can be visualized, k-path be selected and corresponding co-ordinates are exported and K-points file is created. In the current version of CINEMAS, only high symmetry points are exported and labeling has to be done manually.
From the third tab, type of potential(LDA/GGA-PW91/GGA-PBE) can be chosen as well as available option of potentials with different valence. Above holds true if potential files have been configured already.
From the fourth tab, instructions-file(INCAR for VASP) can be prepared, essentially telling DFT-engine(VASP) what to do. CINEMAS can prepare instruction-file in graphical, as well as text mode. All possible code-specific tags have been divided into several categories to help a user lesser experienced with the DFT-code. These categories are further distributed over different user levels such as basic/intermediate/expert. Alternatively expert users can directly type the file in text mode. Additionally any other instruction file can be loaded and modified, or saved for repetitive use in future.