Geometry and electronic setup
| Field or QE keyword | Unit / form | Interpretation |
|---|---|---|
| CELL_PARAMETERS | Three lattice vectors; read the card unit | Defines the simulated cell, including vacuum. |
| ATOMIC_POSITIONS | crystal or a stated length unit | crystal means fractional coordinates in the supplied lattice basis. |
| ecutwfc | Ry | Maximum plane-wave kinetic energy for the wavefunctions. |
| ecutrho | Ry | Charge-density and potential cutoff; converge with the chosen potential. |
| K_POINTS automatic | N1 N2 N3 s1 s2 s3 | Mesh counts and offsets for reciprocal integration; offsets are not fractional atom shifts. |
| K_POINTS crystal_b | Reciprocal path vertices and weights | A line-mode path for band sampling; it is not the SCF integration mesh. |
| nbnd | Integer | Number of electronic states calculated at each k point. |
| tot_charge | Electron-charge convention used by QE | Positive values remove electrons; review periodic-charge treatment. |
| nspin / noncolin / lspinorb | Discrete settings | Spin model and spin-orbit coupling; compatible pseudopotentials are required. |
Convergence and relaxation
| Keyword | Meaning | Interpretation |
|---|---|---|
| conv_thr | SCF threshold in Ry | Controls the estimated electronic energy error; not a force threshold. |
| electron_maxstep | Maximum electronic iterations | A limit; reaching it does not establish convergence. |
| mixing_beta | Density-mixing parameter | Can affect convergence stability; no single value fits all systems. |
| degauss | Smearing width in Ry | An integration/occupation choice, not automatically a physical lattice temperature. |
| forc_conv_thr | Force threshold in Ry/bohr | Used with ionic relaxation; electronic convergence must be sufficiently tight. |
| press | Target pressure in kbar | Relevant to cell relaxation; distinguish applied pressure from residual stress. |
| cell_dofree | Allowed cell degrees of freedom | Defines which metric components can relax; inspect suitability for a slab or constrained strain. |
Numerical entry and units
Numeric fields accept intermediate drafts while you type. Enter or leaving the field commits a valid value; Escape cancels a draft in supported controls. An empty axis bound means automatic, while a zero is an explicit physical bound.
Do not convert all scientific values to display-region formatting. QE inputs, CSV source files, and code use the syntax required by their parser. The interface language does not rewrite a solver input or change a numerical dataset.