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Installing the Code

Mandatory Requirements

  • GNU Make
  • C99 compiler with complex number support (e.g., GCC, Clang, ICC, AMD C-Compiler, MinGW for Windows, PGI).
  • MPI implementation supporting at least MPI-standard 2.1 (e.g., Open-MPI, MPICH, Intel MPI, Microsoft MPI).
  • FFTW-3 or Intel-MKL.
  • HDF5 and NetCDF-C libraries with Parallel I/O support (compiled with MPI).
  • A BLAS library (e.g., OpenBLAS, BLIS, Intel-MKL, or Atlas).

Installation Process

LetzElPhC employs a standard make build system.

  1. Prepare Makefile:

    • Navigate to the sample_config directory.
    • Copy a sample makefile to the src directory and rename it to make.inc.
    • Example: cp sample_config/make_gcc_omp.inc src/make.inc

  2. Edit Configuration:

    • Navigate to the src directory.
    • Edit make.inc to set your compiler, flags, and library paths.

  3. Compile: In the src directory, execute: 

    make
# To compile in parallel (e.g., 4 processes):
make -j 4

Upon successful compilation, the lelphc executable will be created in the src directory.

make.inc Variables Explanation

Below is an annotated example of a make.inc file. Use this to configure your build.

CC                  :=  mpicc
# The MPI C compiler wrapper (e.g., mpicc, mpiicc).

CFLAGS              := -O3
# Compiler flags. -O3 activates high-level optimization.

LD_FLAGS            :=
# Linker flags. Add any necessary library paths or link options here.

# **** OPENMP BUILD (Optional) ***
# To enable multi-threading via OpenMP (recommended for performance):
# 1. Uncomment OPENMP_FLAGS line to define the macro.
# 2. Add the OpenMP compiler flag (e.g., -fopenmp for GCC, -qopenmp for Intel) to both CFLAGS and LD_FLAGS.
# OPENMP_FLAGS      := -DELPH_OMP_PARALLEL_BUILD
# CFLAGS            += -fopenmp 
# LD_FLAGS          += -fopenmp 

# **** DOUBLE PRECISION BUILD (Optional) ***
# By default, LetzElPhC runs in single precision to save memory.
# To run in double precision (higher accuracy, 2x memory usage):
# Uncomment the following line:
# CFLAGS              += -DCOMPILE_ELPH_DOUBLE

# FFTW3 include and libs
FFTW_INC            :=  -I/opt/homebrew/include
FFTW3_LIB           :=  -L/opt/homebrew/lib -lfftw3_threads -lfftw3f -lfftw3f_omp -lfftw3_omp -lfftw3
# Note: If compiling in single precision (default), link against the single precision FFTW libraries (often suffixed with 'f', e.g., -lfftw3f).
# If compiling in double precision, link against the standard double precision FFTW libraries (e.g., -lfftw3).

# BLAS and LAPACK
BLAS_LIB            :=  -L/opt/homebrew/opt/openblas/lib -lopenblas
# Link your BLAS/LAPACK provider. If separate, add both: -lblas -llapack

# NetCDF (Parallel IO required)
NETCDF_INC          :=  -I/path/to/netcdf/include
NETCDF_LIB          :=  -L/path/to/netcdf/lib -lnetcdf
# Ensure your NetCDF library was compiled with parallel I/O support (usually requires HDF5).

# HDF5
HDF5_LIB            :=  -L/path/to/hdf5/lib -lhdf5

# Extra
INC_DIRS            :=
LIBS                :=

Tip

If you have difficulty locating the required libraries, check your YAMBO installation directory. Open the report file located in the config directory; it lists all necessary libraries and include paths used by Yambo, which are generally compatible with LetzElPhC.