Label preperation

System structure file

To train a DeePKS model, users must provide the structures of the interested system(s). Structures can be obtained either from a short AIMD run or by adding structural perturbations on top of an optimized geometry. The structures of the system can be provided via three formats as follows

• (recommended) grouped into atom.npy

  The shape of atom.npy file is [nframes, natoms, 4]:

  • nframes refers to the number of frames (structures) of the interested system;

  • natoms refers to the number of atoms of the interested system, e.g., for single water system, natoms = 3;

  • the last dimension 4 corresponds to the nuclear charge of the given atom and its xyz coordinates (either in Cartesian form or in fractional form, which needs to be specified with keyword coord_type in scf_abacus.yaml).

Note

If coordinates saved in atom.npy are in unit of Bohr, then lattice_constant should be set to 1 in scf_abacus.yaml. If coordinates saved in atom.npy are in unit of Angstrom, then lattice_constant should be set to 1.8897259886 in scf_abacus.yaml. If fractional coordinates are used, lattice_constant also needs to be set accordingly. See ABACUS documentation for more details.

• grouped into coord.npy and type.raw

  coord.npy is very similar to atom.npy with the shape [nframes, natoms, 3]. The only difference is that the nuclear charge is not included in the last dimension, which is included in type.raw instead. Note that this format has not been fully tested for periodic systems.

• single xyz

  Save the xyz coordinate of each frame as single xyz file, e.g., 0000.xyz, 0001.xyz,… Note that this format has not been fully tested for periodic systems.

It should be noted that if the lattice vectors of each frame are not the same, users should specify the lattice vector for each frame via box.npy, of which the shape is [nframe, 9]. If the prepared structures share the same lattice vector, then users may specify it as a keyword in input files. See scf_abacus.yaml for details.

Property labels

To train a DeePKS model, the target energy of the interested system is required, and its format should follow the format of the structure file. Additional properties can also be trained, including force, stress, and bandgap. Note that the bandgap label corresponds to the energy difference between the valence band and the conduction band for each k-point, and currently this label only works for semiconductors with even numbers of electrons. The formats of structure files (taking atom.npy as an example) and the corresponding formats of various property labels are summarized as follows:

Filename	Description	Shape	Unit
atom.npy	structural file, required	[nframes, natoms, 4]	Bohr or Angstrom or fractional
box.npy	lattice vector file, optional	[nframes, 9]	Bohr or Angstrom
energy.npy	energy label, required	[nframes,1]	Hartree
force.npy	force label, optional	[nframes, natoms, 3]	Hartree/Bohr
stress.npy	virial vector file, optional	[nframes, 9]	Hartree
orbital.npy	bandgap label, optional	[nframes,nkpt,1]	Hartree