4. Solvers & calculation types

LatticeMind drives three solver backends. A single project is bound to one solver — LatticeMind does not mix solver vocabularies within a project. The solver is inferred from your prompt (for example “Using NanoDCAL, …”) or set explicitly.

Solver	Status	Summary
RESCU	Primary, stable	Real-space / atomic-orbital Kohn–Sham DFT. The default and most thoroughly tested backend.
NanoDCAL	Supported	LCAO quantum-transport solver. Two-probe devices — transmission, conductance, I–V, scattering states, AC response, thermoelectrics and photocurrent — plus effective mass, complex bands, phonons and ground-state properties. See NanoDCAL support.
VASP	Preview (beta)	Plane-wave DFT for multi-stage workflows.

4.1. RESCU calculation types

LatticeMind supports the following RESCU calculations, and chains them automatically (for example SCF → DOS, or SCF → band structure):

Calculation	What you get
Self-consistent field (SCF)	Ground-state electron density and total energy; the foundation for most other steps.
Band structure	Electronic bands along a k-point path, with automatic high-symmetry path selection. The answer reports RESCU’s own band gap, valence-band maximum and conduction-band minimum, per spin for a collinear run, with the spin splitting of the top valence band. Rectangular and square monolayers get the Γ–X–S–Y–Γ path; standard bulk paths need a primitive cell, and an explicit path of your own is always accepted.
Density of states (DOS)	Total DOS, and projected/local DOS (PDOS/LDOS) via atomic orbitals.
Structural relaxation	Relaxed atomic positions (and cell), via steepest-descent or non-linear conjugate-gradient. The report gives the relaxed lattice parameters, the converged energy, and the force norm across iterations, so you can see whether the geometry actually settled.
DFT+U	Hubbard-corrected DFT for correlated systems (e.g. transition-metal oxides), with a curated U table.
DFPT phonons	Phonon band structures and DOS, and dielectric/IR/Raman response via density functional perturbation theory.
Magnetism	Spin-polarized (collinear) and non-collinear calculations, including spin-orbit coupling. A collinear SCF reports the converged magnetic moment, total and per atom, and the band edges per spin on the SCF mesh. For antiferromagnets seeded with opposite moments, LatticeMind picks a real-space grid that keeps the two sublattices equivalent and reports when their converged moments differ. Elemental Fe, Co and Ni start in their magnetic state: collinear spin, the cited moment per atom, a real-space grid of at most 0.3 Bohr and a 12×12×12 tetrahedron mesh. A seeded moment that converges to zero is reported as a failed magnetic state, not as a result.
Metals	A metal is reported as a metal: a band crossing the Fermi level, or a state inside the smearing window, is named as the reason instead of a gap.
Alloys & defects	Deterministic alloy supercells and point-defect structures, including defect formation-energy workflows.
Surfaces & work functions	Symmetric slabs built from the parent crystal, with the surface cell, layer count and vacuum you ask for. The work function is read from the plane-averaged electrostatic potential and reported alongside the measured value for that surface. Ask for several slab thicknesses in one request to see how the work function converges with thickness.

Note

You do not need to write RESCU keywords yourself. LatticeMind selects the calculation type, parameters, and hand-offs, and renders the input decks. The generated .input files at the project root are standard RESCU decks you can inspect, keep, and re-run.

4.2. VASP calculation types (preview)

Calculation	What you get
SCF	Total energy and the band edges from the occupations: highest filled and lowest empty sampled states, direct or indirect, and the smallest direct gap.
Band structure	Bands along a line path, plotted with the path’s labels (Γ, M, K, …) and, when the occupations verify, referenced to the valence-band maximum with the gap printed. You can set the number of points per path segment (`KPOINTS_LINE_DIVISIONS`, 2–400; 40 by default).
Density of states	Total DOS from a fixed-density run on the SCF charge density.
Spin polarization	Collinear runs (`ISPIN=2`) report band edges per spin channel, the two-channel gap, the spin splitting at each sampled point and the net moment. The density-mixing tags (`AMIX`, `BMIX`, `AMIX_MAG`, `BMIX_MAG`) are available for hard magnetic SCFs.
Relaxation	Ions only (`ISIF=2`) or ions and cell (`ISIF=3`). A variable-cell run reports the starting and relaxed cell lengths and the final pressure, with the Pulay-stress caveat. The relaxed geometry can be handed straight to the next calculation.

Each VASP calculation keeps its native files (INCAR, POSCAR, KPOINTS, POTCAR) in its own folder in the project. Set VASP_PP_PATH to your licensed POTCAR library.

4.3. NanoDCAL in a conversation

NanoDCAL covers ground-state and electronic-structure calculations and two-probe transport; the full list is in NanoDCAL support. New in 0.5 for conversations:

Collinear spin, with an initial polarization declared per atom, so an antiferromagnetic setup needs no hand-edited input.
DFT+U, with a Hubbard parameter block per element.
Complex band structures as a child of an SCF, reported as the energy windows free of propagating modes and the smallest decay rate in each.
Band edges from NanoDCAL band structures: NanoDCAL’s own gap and the per-spin edges along the path.

4.4. How the solver is chosen

From your prompt. “Using NanoDCAL, run a transmission calculation…” binds the project to NanoDCAL; an unqualified DFT request uses RESCU by default.
Explicitly. Choose the solver on the browser’s setup card, or configure the solver commands with latticemind setup (see Settings & configuration reference).

4.5. Choosing between solvers

If you want to…	Use
Electronic structure, phonons, magnetism, defects of a bulk crystal	RESCU
Quantum transport through a two-probe device (transmission, I–V, conductance), effective mass, complex bands	NanoDCAL
A plane-wave cross-check or an existing VASP-based multi-stage workflow	VASP