MIKA

Official Resources

• Homepage: https://wiki.fysik.dtu.dk/mika/
• Documentation: https://wiki.fysik.dtu.dk/mika/
• Source Repository: Distributed via website (GPL)
• License: GNU General Public License

Overview

MIKA (Multigrid Instead of K-spAce) is a collection of Matlab/Octave functions and C++ codes for electronic structure calculations using real-space grid methods (finite difference and multigrid). It includes a DFT solver (RMG) and a time-dependent DFT solver. It is designed for solving the Schrödinger and Poisson equations on real-space grids, particularly useful for transport and large systems without periodic boundary conditions.

Scientific domain: Real-space DFT, multigrid methods, electronic structure
Target user community: Developers of real-space methods, researchers in transport

Theoretical Methods

• Real-space finite difference discretization
• Multigrid acceleration for Poisson/Schrödinger solvers
• Density Functional Theory (DFT)
• Time-Dependent DFT (TDDFT)
• Generalized Poisson equation

Capabilities (CRITICAL)

• RMG: Real-space Multigrid DFT code (included in MIKA suite)
• FD: Finite difference derivatives
• Poisson Solver: Fast multigrid Poisson solver
• Transport: Wavefunction matching for transport calculations (Do calculations for scattering states)
• Jellium: Jellium model calculations

Sources: MIKA website, Comp. Phys. Comm. 128, 1 (2000)

Inputs & Outputs

• Input formats: Matlab/Octave scripts, structure files
• Output data types: Grid data (potential, density), wavefunctions

Interfaces & Ecosystem

• Matlab/Octave: Core environment
• C++: Performance-critical parts
• GPAW: Similar real-space philosophy (developed by related groups at DTU)

Workflow and Usage

1. Define grid and potential in Matlab.
2. Call MIKA solvers (e.g., mg_solve).
3. Analyze wavefunctions on the grid.

Performance Characteristics

• O(N) scaling for Poisson solver
• Efficient for non-periodic systems (clusters, wires)
• Limited by grid memory usage

Application Areas

• Nanowire transport
• Quantum dots
• Method development for real-space DFT
• Jellium clusters

Community and Support

• Developed at CSC (Finland) and DTU (Denmark)
• Legacy code (precursor to modern real-space codes like GPAW/Octopus)
• Open-source

Verification & Sources

Primary sources:

1. Homepage: https://wiki.fysik.dtu.dk/mika/
2. Publication: T. Torsti et al., Comp. Phys. Comm. 162, 167 (2004)

Confidence: VERIFIED

Verification status: ✅ VERIFIED

• Website: ACTIVE (Wiki)
• Documentation: AVAILABLE
• Source: OPEN (GPL)
• Development: STABLE (Legacy/Maintenance)
• Applications: Real-space DFT, multigrid