Prepare the dataset

To perform efficient ab initio electronic structure calculation by DeepH method for a class of large-scale material systems, one needs to design an appropriate dataset of small structures that have close chemical bonding environment with the target large-scale material systems. Therefore, the first step of a DeepH study is to perform the DFT calculation on the above dataset to get the DFT Hamiltonian matrices with the localized basis. DeepH-pack supports DFT results made by ABACUS, OpenMX, FHI-aims or SIESTA and will support HONPAS soon.

Using ABACUS

One needs to perform the DFT calculation with ABACUS to get the Kohn-Sham Hamiltonian output file in the csr format. This output file should be placed in a separate folder for each structure in the dataset. In order to get this csr file, the input file of ABACUS should include keywords like this:

out_mat_hs2   1

Note added: the DeepH-ABACUS interface currently suffers from bug regarding the sparsity pattern of ABACUS’s overlap matrix, which may cause errors in DeepH prediction. We’re currently working on this issue, and this note will be removed once a fix is ready.

Using OpenMX

One needs to perform the DFT calculation with OpenMX to get the Kohn-Sham Hamiltonian output file in a binary form. This binary file should be placed in a separate folder for each structure in the dataset and should be named as openmx.scfout. In order to get this binary file, the input file of OpenMX should include keywords like this:

System.Name   openmx
HS.fileout    On

Besides, it is required to attach the text output of openmx.out to the end of openmx.scfout, which means to run:

cat openmx.out >> openmx.scfout

Using FHI-aims

One needs to perform the DFT calculation with modified FHI-aims to get the Kohn-Sham Hamiltonian output file in text format. This output file should be placed in a separate folder for each structure in the dataset.

Using SIESTA

One needs to perform DFT calculation with SIESTA to get Hamiltonians in binary file named ${System_name}.HSX. To activate this feature, you should include keyword in ${System_name}.fdf file:

SaveHS true

It is also recommended to specify a higher convergence criteria for SCF calculation. We found it sufficient to write in ${System_name}.fdf file:

DM.Tolerence  1.d-9