MIMD Lattice Collaboration (MILC) + Quantum EXpressions (QEX)

This is a fork of the Quantum EXpressions (QEX) lattice field theory framework that contains open-source MILC collaboration code.

• src/alphas: Highly improved staggered quark (HISQ) Hamiltonian (hybrid) Monte Carlo (HMC) with $\boldsymbol{N_{\mathrm{f}}=4}$ degenerate "quark" flavors. HMC implements Hasenbusch preconditioning and utilizes a tree-level Symanzik (Luescher-Weiss) gauge action (one-loop HISQ action with tadpole coefficient $\boldsymbol{u_{0}=1}$); coefficients are set such that $\boldsymbol{\beta \equiv 10/g_{0}^2}$ (MILC convention). Directory also contains software for Yang-Mills gradient flow with arbitrary rectangle actions. Please see README.md under src/alphas for details.

QEX: Quantum EXpressions lattice field theory framework

QEX is a high-level framework for lattice field operations written in the language Nim.

It provides optimized lattice field operations, including SIMD support, for CPU architectures (native GPU support is currently experimental). Since Nim compiles to native C/C++, directly calling any C/C++ lattice code or library from QEX is relatively easy to do.

Some simple code examples are here ex0.nim ex1.nim.

It currently supports

• U(1), SU(2..4) gauge fields in any dimension
• SciDAC I/O
• Gauge fixing
• Staggered solver and forces (Asqtad, HISQ, nHYP)
• Wilson solver (no clover yet)
• Interface for Chroma, Grid, QUDA interoperability

Installation guide: INSTALL.md

Build guide: BUILD.md

Further examples:

• tests/examples