Input file reference

The input file consists of keyword = value lines. # starts a comment and blank lines are ignored. Keywords and enumerated values (units, solver names, on/off switches) are case-insensitive. File-name values are the exception: they are taken verbatim and are therefore case-sensitive. Defining the same keyword twice is an error.

A typical input file (from examples/1DKronigPenney/input.in, annotated):

# 1D Kronig-Penney model, periodic, with k-point sampling
potential-file = potential.dat     # grid potential (required)
stencil        = 9                 # 9-point finite-difference stencil
reduced-mass   = 23.06000881918738 # in units of mass-unit
mass-unit      = me                # electron masses
coord-unit     = angstrom          # unit of the coordinates in potential.dat
potential-unit = ev                # unit of the potential values in potential.dat
n-eigenvalues  = 10                # number of states to compute
periodic       = true              # periodic boundary conditions
k-points       = 10                # k-points from Gamma to the zone boundary

Keywords

The only required keyword is potential-file. All others have defaults:

Keyword	Meaning	Allowed values	Default
`potential-file`	Path to the grid-potential file	file path	required
`potential-unit`	Energy unit of the potential values	`hartree`, `ev`, `kj/mol`, `kcal/mol`	`hartree`
`coord-unit`	Length unit of the grid coordinates	`angstrom`, `nm`, `bohr`	`angstrom`
`mass-unit`	Unit of the reduced masses (`unit` and `g/mol` both mean the atomic mass unit; `me` and `m_e` both mean the electron mass)	`unit`, `g/mol`, `me`, `m_e`	`unit`
`stencil`	Number of finite-difference stencil points (see note below)	`3`, `5`, `7`, `9`, `11`, `13`	`9`
`stencil-laplace`	Stencil size for the Laplacian only (overrides `stencil`)	`3`, `5`, `7`, `9`, `11`, `13`	value of `stencil`
`stencil-nabla`	Stencil size for the gradient only (overrides `stencil`; the gradient matrix is used for periodic/k-point runs)	`3`, `5`, `7`, `9`, `11`	value of `stencil`
`reduced-mass`	Reduced mass per dimension, comma- or space-separated; a single value is applied to all dimensions	real numbers	`1.0`
`periodic`	Periodic boundary conditions per dimension, comma- or space-separated; a single value is applied to all dimensions	`true`, `false`	`false`
`n-eigenvalues`	Number of eigenvalues/eigenvectors to compute	integer >= 1	`5`
`k-points`	Number of k-points sampled per direction between the Gamma point and the Brillouin-zone boundary; if omitted, a single calculation at k = 0 is performed	integer > 1	not set
`datapoints`	Number of grid points per dimension, comma- or space-separated (e.g. `datapoints = 20, 30`)	integers	required for 2D/3D; in 1D taken from the potential file
`band-structure`	Compute the band structure along the path through the high-symmetry points of the Brillouin zone (requires `k-points`)	`on`, `true`, `off`, `false`	`off`
`solver`	Eigensolver backend	`arpack`, `krylov`, `lu`	`arpack`
`output-file`	Name of the log file	file path	`Numerov.out`
`timings-file`	Name of the timings file	file path	`timings.out`
`read-k-points`	Read the k-points from a file instead of generating them (accepted but not yet implemented)	`true`, `false`	`false`
`k-points-file`	k-point file for `read-k-points` (accepted but not yet implemented — the file is ignored with a warning)	file path	not set

Stencil sizes and dimensionality

Not every stencil size is implemented for every dimensionality: the 13-point Laplacian is not available in 2D or 3D, and the 3-point Laplacian is not available in 3D. Unsupported combinations throw an ArgumentError when the operator matrix is built.

Potential file format

The potential is given on a regular grid as whitespace-separated columns, one grid point per line: first the coordinates, then the potential value. # starts a comment and blank lines are ignored. The dimensionality of the problem is inferred from the number of columns:

# 1D:  x  V(x)
-10.0   50.0
 -9.9   49.005
 ...

# 2D:  x  y  V(x,y)
# 3D:  x  y  z  V(x,y,z)

Coordinates are interpreted in coord-unit and potential values in potential-unit; internally everything is converted to atomic units. For 2D and 3D potentials the number of grid points per dimension must be given explicitly with the datapoints keyword.