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DMRG codes by other groups

Stoudenmire and White: ITensor is "[a] C++ library for creating efficient and flexible physics simulations based on tensor product wavefunctions."

Related codes by my group

PsimagLite

PsimagLite is a light C++ library and framework that the other applications listed here depend on.

You can also use PsimagLite in your own C++ to simplify things and do complicated stuff in just a few lines of C++ code, as if you were using Mathematica or Maxima but faster and programatically! Features are:

• Compute AkimaSplines
• Call BLAS and LAPACK with C++ wrappers
• Use an efficient Chebyshev solver (replaces Lanczos)
• Compute Continued Fractions
• Use a Davidson solver (not ready)
• Call GSL functions from C++ Wrappers which allows your application to compile even without the GSL.
• Do complicated numerical integrations in just a few lines of C++ code
• Use an efficient Lanczos solver and polished over many years
• Use a C++ Matrix class with direct BLAS/LAPACK interfacing
• Measure your applications' Memory and CPU usage
• Generate pseudo-random numbers with a MersenneTwister
• Minimize functions of any number of variables (C++ frontend with GSL backend)
• Parallelize your loops with Shared Memory
• Generate Permutations
• Indicate progress and timings for your C++ app
• Decode and Encode Base64
• Generate predictable pseudo-random numbers for debugging your Monte Carlo
• Find the root of a function with bisection or conjugate gradient in just a few lines of C++
• Trap all heap allocations that your C++ app makes with non-intrusive techniques
• Do bit manipulation
• Integrate with Runge Kutta
• Do Sparse Matrix operations efficiently

DMRG++

DMRG++ is a free and open source implementation of the DMRG algorithm. Features are

• Very few dependencies: You don't need to install the kitchen sink to compile it
• Generic DMRG engine: isolate models and geometries
• Local and SU(2) symmetries: decrease your computation time
• Configurable finite-algorithm sweeps: sweep the lattice in a flexible way
• Post-processing of observables: run once, measure any number of times
• Concurrency support: run with MPI, pthreads or simply serially
• Full checkpointing support: re-start your runs
• Testsuite: when adding feature X don't break feature Y
• Time Evolution: compute time-dependent observables with state-of-the-art techniques
• Temperature Dependence: Use the White's METTS algorithm
• Spectral Functions: Use Different Dynamics methods including Correction Vector
• Oracles: Gauge your accuracy with pure Lanczos and other auxiliary codes to match (use the same input)

FreeFermions

Ever wanted to quickly run a code that would give you the braket <gs|c_i,up c⁺_j,up|gs> for a generic tight-binding Hamiltonian (”free system“)? Well, FreeFermions is the answer! But you can do much more! Orbitals? no problem! You need a holon-doublon operator inside the braket? We got you covered! Complicated matrix of hoppings for a difficult geometry? We have it! You need to time evolve inside the braket? We can do that too! You need to warm the braket to finite temperature? Sure. Very very few dependencies to compile. Plus an easy interface: You can almost copy your braket from paper to computer, and it will get computed.

LanczosPlusPlus

You've got a strongly correlated model like Hubbard or t-J or Heisenberg. You want ground state correlations on a not too big lattice. Then, take a look at LanczosPlusPlus, a Hamiltonian code with a Lanczos Solver or Chebyshev solver or a full dense matrix solver. Just use a simple input file, and run it like ./lanczos -f input.inp. Large model and geometry selection. Or input your own geometry as a matrix of hoppings or exchanges. Dynamical correlations are also supported.

BetheAnsatz

BetheAnsatz is a free and open source Bethe ansatz code. It supports Heisenberg and Hubbard at zero and finite temperature. It supports the t-J model at the fully symmetric point where the Bethe ansatz is possible.

QPT++

QPT++ is a free and open source zero temperature quantum perturbation expansion code. It does symbolic expansion, equation simplification and also numerics. It is the newest code of this list and more features will be added in the future.