Relaxation-get-started-and-input-examples.md

Relaxation get started and input examples

The relaxation of a structure should be carried out before calculating all other properties.

First, we need input parameter file and we name it relax.json here. All the relaxation calculations should be taken either by VASP, ABACUS, or LAMMPS. Here are two input examples for VASP and LAMMPS respectively.

An example of the input file for relaxation by VASP:

{
    "structures":            ["confs/std-*"],
    "interaction": {
            "type":           "vasp",
            "incar":          "vasp_input/INCAR",
            "potcar_prefix":  "vasp_input",
            "potcars":       {"Al": "POTCAR.al"}
	},
    "relaxation": {
            "cal_type":       "relaxation",
            "cal_setting":   {"relax_pos":       true,
                              "relax_shape":     true,
                              "relax_vol":       true,
                              "ediff":           1e-6,
                              "ediffg":         -0.01,
                              "encut":           650,
                              "kspacing":        0.1,
                              "kgamma":          false}
	}
}

Key words	data structure	example	description
structures	List of String	["confs/std-*"]	path of different structures
interaction	Dict	See above	description of the task type and atomic interaction
type	String	"vasp"	task type
incar	String	"vasp_input/INCAR"	path for INCAR file in vasp
potcar_prefix	String	"vasp_input"	prefix of path for POTCAR file in vasp, default = ""
potcars	Dict	{"Al": "POTCAR.al"}	key is element type and value is potcar name
relaxation	Dict	See above	calculation type and setting for relaxation
cal_type	String	"relaxation" or "static"	calculation type
cal_setting	Dict	See above	calculation setting
relax_pos	Boolean	true	relax atomic position or not, default = true for relaxation
relax_shape	Boolean	true	relax box shape or not, default = true for relaxation
relax_vol	Boolean	true	relax box volume or not, default = true for relaxation
ediff	Float	1e-6	set EDIFF parameter in INCAR files
ediffg	Float	-0.01	set EDIFFG parameter in INCAR files
encut	Int	650	set encut parameter in INCAR files
kspacing	Float	0.1	set KSPACING parameter in INCAR files
kgamma	Boolean	false	set KGAMMA parameter in INCAR files

An example of the input file for relaxation by LAMMPS:

{
    "structures":         ["confs/std-*"],
    "interaction": {
            "type":        "deepmd",
            "model":       "frozen_model.pb",
            "in_lammps":   "lammps_input/in.lammps",
            "type_map":   {"Al": 0}
	},
    "relaxation": {
            "cal_setting":{"etol": 0,
                           "ftol": 1e-10,
                           "maxiter": 5000,
                           "maximal": 500000}
	}
}

Other key words different from vasp:

Key words	data structure	example	description
model	String or List of String	"frozen_model.pb"	model file for atomic interaction
in_lammps	String	"lammps_input/in.lammps"	input file for lammps commands
type_map	Dict	{"Al": 0}	key is element type and value is type number. DP starts from 0, others starts from 1
etol	Float	0	stopping tolerance for energy
ftol	Float	1e-10	stopping tolerance for force
maxiter	Int	5000	max iterations of minimizer
maxeval	Int	500000	max number of force/energy evaluations

For LAMMPS relaxation and all the property calculations, package will help to generate in.lammps file for user automatically according to the property type. We can also make the final changes in the minimize setting (minimize etol ftol maxiter maxeval) in in.lammps. In addition, users can apply the input file for lammps commands in the interaction part. For further information of the LAMMPS relaxation, we refer users to minimize command.