12.10 LQCD¶

12.10.1 Introduction to LQCD¶

Quantum Chromodynamics (QCD) is the fundamental theory that describes the strong interaction and hadron structure. Because QCD involves strong coupling, solving it rigorously is a highly challenging theoretical problem. Lattice QCD (LQCD) is a numerical gauge-field-theory method that studies the properties of quarks and gluons from the first principles of QCD.

12.10.2 Common Used Softwares¶

Currently common used LQCD softwares in IHEP:

Chroma: developed by USQCD Collaberations
QUDA：supported by NVIDIA, using GPU to perform lqcd calculations combined with sChroma。
GWU-Code：developed by χQCD Collaberations.

12.10.3 LQCD Software Usage¶

12.10.3.1 Basics and Software Compilation¶

https://github.com/IHEP-LQCD/Tutorial provides a detailed guide to the computing basics of lattice QCD and to compiling the software.

12.10.3.2 Software Versions and Storage Location¶

Chroma-related software, the LLVM compiler, and MPI libraries are managed with module. Add the modulefile path to .bashrc with:

echo "module use /hpcfs/lqcd/qcd/modulefiles" >> ~/.bashrc
source ~/.bashrc

You can then list the compiled and installed software with:

module av

Example output:

---------------------------------------------------------- /hpcfs/lqcd/qcd/modulefiles -----------------------------------------------------------
lqcd/chroma/double/with-qdpjit-quda-mpi  lqcd/cuda/12.4  lqcd/llvm/22.1.8  lqcd/mpi/openmpi/5.0.10/cuda12.4-gcc11  lqcd/quda/1.1.0/cuda12.4-openmpi5.0.10

12.10.3.3 How to Use the Software¶

Chroma¶

Chroma is compiled in double precision. Load the runtime environment and dependencies with module load lqcd/chroma/double/with-qdpjit-quda-mpi. Jobs are submitted via SLURM. Below is a simple job script:

#! /bin/bash
#### Job Queue
#SBATCH --partition=gpu

#### Group Name： lqcd
#SBATCH --account=lqcd

#### CPU Cores
#SBATCH --ntasks=8

#### Output redirection
#SBATCH --output=<some_writable_directory>/job-%j.out
#SBATCH --job-name=gpu_test

##### Specify memory to use, or slurm will allocate all available memory
#SBATCH --mem-per-cpu=2048

##### Specify how many GPU cards to use,  8 in total per node.
#SBATCH --gres=gpu:v100:2

module use /hpcfs/lqcd/qcd/modulefiles
module load lqcd/chroma/double/with-qdpjit-quda-mpi

mpirun -np 2 chroma -geom 1 1 1 2 -i sample.in.xml -o sample.out.xml

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