diff --git a/CMakeLists.txt b/CMakeLists.txt
index e4b337d..11c1fbf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,479 +1,349 @@
-project(MESS C CXX)
-cmake_minimum_required(VERSION 3.16)
-
+# =============================================================================
+# Project Definition
+# =============================================================================
+cmake_minimum_required(VERSION 3.22)
+project(MESS LANGUAGES C CXX Fortran)
+
+# =============================================================================
+# Modern CMake Practices & Project-Wide Settings
+# =============================================================================
+# Set C++ standard for all targets in the project
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS}")
+set(CMAKE_CXX_EXTENSIONS OFF)
 
-# Options for automatic dependency handling
-option(AUTO_DOWNLOAD_DEPENDENCIES "Automatically download and build missing dependencies" ON)
-option(USE_SYSTEM_LIBS "Try to use system libraries before downloading" ON)
+# Use a dedicated folder for external projects to keep the build directory clean
+set(EXTERNAL_INSTALL_LOCATION ${CMAKE_BINARY_DIR}/_deps)
 
-# Directory for downloaded and built dependencies
-set(EXTERNAL_INSTALL_LOCATION ${CMAKE_BINARY_DIR}/external)
+# Include required modules
+include(FetchContent)
 include(ExternalProject)
 
-# External library URLs and versions
-set(OPENBLAS_GIT_URL "https://github.com/OpenMathLib/OpenBLAS.git")
-set(OPENBLAS_VERSION "v0.3.21")
-set(SLATEC_URL "https://www.netlib.org/slatec/slatec_src.tgz")
-set(GSL_URL "https://ftp.gnu.org/gnu/gsl/gsl-2.7.tar.gz")
-set(QD_URL "https://www.davidhbailey.com/dhbsoftware/qd-2.3.23.tar.gz")
-set(QD_SHA256 "b3eaf41ce413ec08f348ee73e606bd3ff9203e411c377c3c0467f89acf69ee26")
-
-# Check for direct SLATEC build
-if(USE_DIRECT_SLATEC)
-  message(STATUS "Using direct SLATEC build")
-  if(EXISTS "${CMAKE_SOURCE_DIR}/external/lib/libslatec.a")
-    set(SLATEC "${CMAKE_SOURCE_DIR}/external/lib/libslatec.a")
-    message(STATUS "Found direct SLATEC: ${SLATEC}")
-  else()
-    message(WARNING "Direct SLATEC build enabled but library not found. Please run ./slatec_direct.sh first.")
-    message(STATUS "Falling back to regular SLATEC build")
-    set(USE_DIRECT_SLATEC OFF)
-  endif()
+# =============================================================================
+# Project Options
+# =============================================================================
+option(USE_MKL "Use Intel MKL instead of OpenBLAS" OFF)
+option(USE_INT64 "Use 64-bit integers for BLAS/LAPACK (ILP64 interface)" OFF)
+option(USE_CONDA_LIBS "Use libraries from conda environment" OFF)
+# option(USE_DIRECT_CBLAS "Use direct CBLAS instead of GSL's wrapper" OFF) # This option was unused.
+
+# =============================================================================
+# Build Configuration
+# =============================================================================
+# Set default build type to Release if not specified
+if(NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE Release CACHE STRING "Build type" FORCE)
 endif()
 
-# Function to conditionally download and build a dependency
-function(handle_dependency name)
-  if(NOT ${name}_FOUND AND AUTO_DOWNLOAD_DEPENDENCIES)
-    message(STATUS "Will download and build ${name}")
-    set(${name}_FOUND TRUE PARENT_SCOPE)
-    set(${name}_DOWNLOADED TRUE PARENT_SCOPE)
-  endif()
-endfunction()
-
-# Find BLAS and LAPACK
-if(USE_SYSTEM_LIBS)
-  find_package(BLAS QUIET)
-  find_package(LAPACK QUIET)
-else()
-  set(BLAS_FOUND FALSE)
-  set(LAPACK_FOUND FALSE)
-endif()
-
-# If BLAS/LAPACK not found, use OpenBLAS which provides both
-if((NOT BLAS_FOUND OR NOT LAPACK_FOUND) AND AUTO_DOWNLOAD_DEPENDENCIES)
-  message(STATUS "BLAS or LAPACK not found. Will download and build OpenBLAS.")
-  set(BLAS_FOUND TRUE)
-  set(LAPACK_FOUND TRUE)
-  
-  ExternalProject_Add(
-    openblas
-    GIT_REPOSITORY ${OPENBLAS_GIT_URL}
-    GIT_TAG ${OPENBLAS_VERSION}
-    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EXTERNAL_INSTALL_LOCATION} -DCMAKE_C_FLAGS="-Wno-misleading-indentation"
-    BUILD_COMMAND $(MAKE)
-    INSTALL_COMMAND $(MAKE) PREFIX=${EXTERNAL_INSTALL_LOCATION} install
-  )
+# Print build configuration
+message(STATUS "==========================================")
+message(STATUS "MESS Build Configuration")
+message(STATUS "==========================================")
+message(STATUS "Build Type: ${CMAKE_BUILD_TYPE}")
+message(STATUS "C++ Standard: ${CMAKE_CXX_STANDARD}")
+message(STATUS "USE_MKL: ${USE_MKL}")
+message(STATUS "USE_INT64: ${USE_INT64}")
+message(STATUS "USE_CONDA_LIBS: ${USE_CONDA_LIBS}")
+message(STATUS "==========================================")
+
+# =============================================================================
+# Find Dependencies (BLAS, LAPACK, GSL, MPI, etc.)
+# =============================================================================
+include(FetchContent)
+
+# --- BLAS / LAPACK Configuration ---
+message(STATUS "Configuring BLAS and LAPACK...")
+
+if(USE_CONDA_LIBS)
+  message(STATUS "Using conda environment libraries")
+  set(CONDA_LIB_PATH "/home/keceli/miniconda3/envs/kmess-env/lib")
   
-  set(BLAS_LIBRARIES ${EXTERNAL_INSTALL_LOCATION}/lib/libopenblas.so)
-  set(LAPACK_LIBRARIES ${EXTERNAL_INSTALL_LOCATION}/lib/libopenblas.so)
-  set(OPENBLAS_DOWNLOADED TRUE)
-else()
-  message(STATUS "Found BLAS: ${BLAS_LIBRARIES}")
-  message(STATUS "Found LAPACK: ${LAPACK_LIBRARIES}")
-endif()
-
-# Find Fortran compilation capabilities
-# This tells CMake to enable Fortran language for our project
-enable_language(Fortran OPTIONAL)
-
-# Find SLATEC
-if(USE_SYSTEM_LIBS)
-  find_library(SLATEC NAMES slatec libslatec QUIET)
-endif()
-
-if(NOT SLATEC AND AUTO_DOWNLOAD_DEPENDENCIES)
-  message(STATUS "SLATEC not found. Will download and build it.")
-
-  # Create SLATEC wrapper file content for missing C interfaces
-  file(WRITE ${CMAKE_BINARY_DIR}/slatec_wrapper.f "
-! Explicit wrapper for SLATEC functions that need C-compatible interfaces
-      subroutine davint(x, y, n, xlo, xup, ans, ierr)
-      implicit none
-      integer n, ierr
-      double precision x(n), y(n), xlo, xup, ans
-      call davint_(x, y, n, xlo, xup, ans, ierr)
-      return
-      end
-
-      subroutine ddeabm(f, neq, t, y, tout, info, rtol, atol, idid,
-     &                 rwork, lrw, iwork, liw, rpar, ipar)
-      external f
-      integer neq, info(*), idid, lrw, iwork(*), liw
-      double precision t, y(*), tout, rtol(*), atol(*), rwork(*)
-      integer ipar(*)
-      double precision rpar(*)
-      call ddeabm_(f, neq, t, y, tout, info, rtol, atol, idid,
-     &            rwork, lrw, iwork, liw, rpar, ipar)
-      return
-      end
-
-      subroutine dbint4(x, y, n, ibcl, ibcr, fbcl, fbcr, kntopt, t, nc, 
-     &                 bc, ws, lws, ierr)
-      integer n, ibcl, ibcr, kntopt, nc, lws, ierr
-      double precision x(*), y(*), fbcl, fbcr, t(*), bc(*), ws(*)
-      call dbint4_(x, y, n, ibcl, ibcr, fbcl, fbcr, kntopt, t, nc, 
-     &            bc, ws, lws, ierr)
-      return
-      end
-
-      function dbvalu(t, a, n, k, ideriv, x, inbv, work)
-      integer n, k, ideriv, inbv
-      double precision t(*), a(*), x, work(*), dbvalu
-      dbvalu = dbvalu_(t, a, n, k, ideriv, x, inbv, work)
-      return
-      end
-")
-
-  # Create build script for SLATEC
-  file(WRITE ${CMAKE_BINARY_DIR}/build_slatec.sh "#!/bin/sh
-set -e
-# Use gfortran as default Fortran compiler if not specified
-FC=${CMAKE_Fortran_COMPILER}
-if [ -z \"$FC\" ]; then
-  FC=gfortran
-fi
-FFLAGS='-O2 -fPIC -fdefault-real-8 -fdefault-double-8 -std=legacy'
-AR=ar
-
-echo 'Compiling SLATEC modules...'
-for f in *.f; do
-  echo \"Compiling $f...\"
-  $FC $FFLAGS -c $f || exit 1
-done
-
-echo 'Creating library...'
-$AR rcs libslatec.a *.o
-echo 'Build complete'
-")
-
-  # Set up SLATEC build with more detailed configuration for reproducibility
-  set(SLATEC_SOURCE_DIR ${CMAKE_BINARY_DIR}/slatec_src)
-  set(SLATEC_BUILD_DIR ${CMAKE_BINARY_DIR}/slatec_build)
-  
-  include(ExternalProject)
-  ExternalProject_Add(
-    slatec_external
-    URL ${SLATEC_URL}
-    DOWNLOAD_DIR ${CMAKE_BINARY_DIR}/downloads
-    SOURCE_DIR ${SLATEC_SOURCE_DIR}
-    BINARY_DIR ${SLATEC_BUILD_DIR}
-    # Configure step - create a simpler setup
-    CONFIGURE_COMMAND ${CMAKE_COMMAND} -E copy_directory ${SLATEC_SOURCE_DIR} ${SLATEC_BUILD_DIR}
-                      # Copy wrapper file
-                      COMMAND ${CMAKE_COMMAND} -E copy_if_different 
-                              ${CMAKE_BINARY_DIR}/slatec_wrapper.f ${SLATEC_BUILD_DIR}/
-                      # Copy build script
-                      COMMAND ${CMAKE_COMMAND} -E copy_if_different 
-                              ${CMAKE_BINARY_DIR}/build_slatec.sh ${SLATEC_BUILD_DIR}/
-                      # Make build script executable
-                      COMMAND chmod +x ${SLATEC_BUILD_DIR}/build_slatec.sh
-    # Build step - run the build script
-    BUILD_COMMAND ${SLATEC_BUILD_DIR}/build_slatec.sh
-    # Install step - copy built library
-    INSTALL_COMMAND ${CMAKE_COMMAND} -E copy_if_different 
-                    ${SLATEC_BUILD_DIR}/libslatec.a ${EXTERNAL_INSTALL_LOCATION}/lib/libslatec.a
-    # Disable updates
-    UPDATE_COMMAND ""
-    # Logging
-    LOG_DOWNLOAD ON
-    LOG_CONFIGURE ON
-    LOG_BUILD ON
-    LOG_INSTALL ON
-  )
-  
-  set(SLATEC ${EXTERNAL_INSTALL_LOCATION}/lib/libslatec.a)
-  set(SLATEC_DOWNLOADED TRUE)
-else()
-  message(STATUS "Found SLATEC: ${SLATEC}")
-endif()
-
-# Find Fortran libraries needed for SLATEC
-# Try to find Intel Fortran runtime
-find_library(IFORT_LIBRARY NAMES 
-  ifcore ifport ifcoremt ifportmt
-  PATHS
-  /opt/aurora/24.347.0/oneapi/compiler/latest/lib
-  /opt/aurora/24.347.0/oneapi/compiler/latest/lib/intel64
-  /opt/intel/oneapi/compiler/latest/lib
-  /opt/intel/oneapi/compiler/latest/lib/intel64
-)
-
-if(IFORT_LIBRARY)
-  message(STATUS "Found Intel Fortran runtime: ${IFORT_LIBRARY}")
-  set(FORTRAN_LIBRARIES ${IFORT_LIBRARY})
+  if(USE_MKL)
+    message(STATUS "Using Intel MKL from conda")
+    # Use explicit MKL libraries to ensure proper 64-bit integer support
+    if(USE_INT64)
+    set(BLAS_LIBRARIES 
+        ${CONDA_LIB_PATH}/libmkl_intel_ilp64.so
+        ${CONDA_LIB_PATH}/libmkl_gnu_thread.so
+        ${CONDA_LIB_PATH}/libmkl_core.so
+        m
+        dl
+        gomp
+      )
+      set(LAPACK_LIBRARIES ${BLAS_LIBRARIES})
+      message(STATUS "  - Using 64-bit integers (ILP64)")
+    else()
+    set(BLAS_LIBRARIES 
+        ${CONDA_LIB_PATH}/libmkl_intel_lp64.so
+        ${CONDA_LIB_PATH}/libmkl_gnu_thread.so
+        ${CONDA_LIB_PATH}/libmkl_core.so
+        m
+        dl
+        gomp
+      )
+      set(LAPACK_LIBRARIES ${BLAS_LIBRARIES})
+      message(STATUS "  - Using 32-bit integers (LP64)")
+    endif()
+  else()
+    message(STATUS "Using OpenBLAS from conda")
+    set(BLAS_LIBRARIES ${CONDA_LIB_PATH}/libopenblas.so)
+    set(LAPACK_LIBRARIES ${CONDA_LIB_PATH}/libopenblas.so)
+    if(USE_INT64)
+      message(STATUS "  - Using 64-bit integers (ILP64)")
+    else()
+      message(STATUS "  - Using 32-bit integers (LP64)")
+    endif()
+  endif()
+elseif(USE_MKL)
+  message(STATUS "Using Intel MKL")
+  if(USE_INT64)
+    set(BLAS_LIBRARIES 
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_intel_ilp64.so
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_gnu_thread.so
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_core.so
+      m
+      dl
+      gomp
+    )
+  set(LAPACK_LIBRARIES ${BLAS_LIBRARIES})
+    message(STATUS "  - Using 64-bit integers (ILP64)")
+  else()
+    set(BLAS_LIBRARIES 
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_intel_lp64.so
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_gnu_thread.so
+      /opt/intel/oneapi/mkl/latest/lib/intel64/libmkl_core.so
+      m
+      dl
+      gomp
+    )
+  set(LAPACK_LIBRARIES ${BLAS_LIBRARIES})
+    message(STATUS "  - Using 32-bit integers (LP64)")
+  endif()
 else()
-  message(WARNING "Intel Fortran runtime not found, will try gfortran")
-  # Fall back to gfortran if Intel runtime not found
-  find_library(GFORTRAN_LIBRARY NAMES 
-    gfortran libgfortran libgfortran.so.5 libgfortran.so.4 libgfortran.so.3
-    PATHS
-    /usr/lib
-    /usr/lib64
-    /usr/lib/gcc
-    /usr/local/lib
-    /usr/local/lib64
-    /usr/lib/x86_64-linux-gnu
-    /lib/x86_64-linux-gnu
-    PATH_SUFFIXES gcc/x86_64-linux-gnu/10 gcc/x86_64-linux-gnu/9 gcc/x86_64-linux-gnu/8 gcc/x86_64-linux-gnu/7
-  )
-  if(GFORTRAN_LIBRARY)
-    message(STATUS "Found gfortran: ${GFORTRAN_LIBRARY}")
-    set(FORTRAN_LIBRARIES ${GFORTRAN_LIBRARY})
+  message(STATUS "Using OpenBLAS")
+  set(BLAS_LIBRARIES /usr/lib/x86_64-linux-gnu/libopenblas.so)
+  set(LAPACK_LIBRARIES /usr/lib/x86_64-linux-gnu/libopenblas.so)
+  if(USE_INT64)
+    message(STATUS "  - Using 64-bit integers (ILP64)")
   else()
-    message(FATAL_ERROR "No Fortran runtime found")
+    message(STATUS "  - Using 32-bit integers (LP64)")
   endif()
 endif()
 
-# Find optional quadmath library (often needed with gfortran)
-find_library(QUADMATH_LIBRARY NAMES quadmath)
-if(QUADMATH_LIBRARY)
-  message(STATUS "Found quadmath: ${QUADMATH_LIBRARY}")
-  list(APPEND FORTRAN_LIBRARIES ${QUADMATH_LIBRARY})
-endif()
+message(STATUS "BLAS Libraries: ${BLAS_LIBRARIES}")
+message(STATUS "LAPACK Libraries: ${LAPACK_LIBRARIES}")
 
-# Set up link libraries for SLATEC
-set(FORTRAN_LIBRARIES ${FORTRAN_LIBRARIES})
 
-# Find GSL
-if(USE_SYSTEM_LIBS)
+# --- GSL (GNU Scientific Library) ---
+# First, try to find an installed version. If not found, download and build it.
+if(USE_CONDA_LIBS)
+  message(STATUS "Using GSL from conda environment")
+  set(GSL_INCLUDE_DIRS "/home/keceli/miniconda3/envs/kmess-env/include")
+  set(GSL_LIBRARIES "/home/keceli/miniconda3/envs/kmess-env/lib/libgsl.so")
+  set(GSL_DOWNLOADED TRUE)
+else()
   find_package(GSL QUIET)
-endif()
+  if(NOT GSL_FOUND)
+    message(STATUS "GSL not found. Building from source...")
+  if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.24")
+    FetchContent_Declare(
+      gsl_external
+      URL "https://ftp.gnu.org/gnu/gsl/gsl-2.8.tar.gz"
+      URL_HASH SHA256=6a99eeed15632c6354895b1dd542ed5a855c0f15d9ad1326c6fe2b2c9e423190
+      DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+    )
+  else()
+    FetchContent_Declare(
+      gsl_external
+      URL "https://ftp.gnu.org/gnu/gsl/gsl-2.8.tar.gz"
+      URL_HASH SHA256=6a99eeed15632c6354895b1dd542ed5a855c0f15d9ad1326c6fe2b2c9e423190
+    )
+  endif()
+  FetchContent_MakeAvailable(gsl_external)
+
+  # Configure GSL with internal CBLAS (more reliable for CI)
+  set(GSL_CONFIGURE_OPTIONS
+    "--prefix=${EXTERNAL_INSTALL_LOCATION}"
+    "--disable-shared"
+    "--enable-static"
+    "--with-cblas=internal"
+  )
 
-if(NOT GSL_FOUND AND AUTO_DOWNLOAD_DEPENDENCIES)
-  message(STATUS "GSL not found. Will download and build it.")
   ExternalProject_Add(
-    gsl_external
-    URL ${GSL_URL}
-    CONFIGURE_COMMAND <SOURCE_DIR>/configure --prefix=${EXTERNAL_INSTALL_LOCATION}
-    BUILD_COMMAND make
-    INSTALL_COMMAND make install
+    gsl_project
+    SOURCE_DIR ${gsl_external_SOURCE_DIR}
+    BINARY_DIR ${gsl_external_BINARY_DIR}
+    CONFIGURE_COMMAND <SOURCE_DIR>/configure ${GSL_CONFIGURE_OPTIONS}
+    BUILD_COMMAND $(MAKE)
+    INSTALL_COMMAND $(MAKE) install
+    LOG_CONFIGURE TRUE
+    LOG_BUILD TRUE
+    LOG_INSTALL TRUE
   )
+
   set(GSL_INCLUDE_DIRS ${EXTERNAL_INSTALL_LOCATION}/include)
-  set(GSL_LIBRARIES ${EXTERNAL_INSTALL_LOCATION}/lib/libgsl.so)
-  include_directories(${GSL_INCLUDE_DIRS})
+    set(GSL_LIBRARIES ${EXTERNAL_INSTALL_LOCATION}/lib/libgsl.a)
   set(GSL_DOWNLOADED TRUE)
-  set(GSL_FOUND TRUE)
 else()
   message(STATUS "Found GSL: ${GSL_LIBRARIES}")
 endif()
-
-# Find QD
-if(USE_SYSTEM_LIBS)
-  find_library(QD NAMES qd libqd libqd.a QUIET)
 endif()
 
-if(NOT QD AND AUTO_DOWNLOAD_DEPENDENCIES)
-  message(STATUS "QD not found. Will download and build it.")
-  ExternalProject_Add(
-    qd_external
-    URL ${QD_URL}
-    URL_HASH SHA256=${QD_SHA256}
-    CONFIGURE_COMMAND <SOURCE_DIR>/configure --prefix=${EXTERNAL_INSTALL_LOCATION}
-    BUILD_COMMAND make
-    INSTALL_COMMAND make install
-  )
-  set(QD ${EXTERNAL_INSTALL_LOCATION}/lib/libqd.a)
-  set(QD_DOWNLOADED TRUE)
+
+# --- SLATEC (Common Mathematical Library) ---
+# First, try to find an installed version. If not found, download and build it.
+find_library(SLATEC_LIBRARY NAMES slatec libslatec)
+if(NOT SLATEC_LIBRARY)
+    message(STATUS "SLATEC not found. Building from source...")
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.24")
+      FetchContent_Declare(
+          slatec_external
+          URL "http://www.netlib.org/slatec/slatec_src.tgz"
+          URL_HASH SHA1=6100817113c115778eddec5811065be818157554
+          DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+      )
+    else()
+      FetchContent_Declare(
+          slatec_external
+          URL "http://www.netlib.org/slatec/slatec_src.tgz"
+          URL_HASH SHA1=6100817113c115778eddec5811065be818157554
+      )
+    endif()
+    FetchContent_Populate(slatec_external)
+
+    # Glob all Fortran sources from the downloaded content
+    file(GLOB SLATEC_SOURCES "${slatec_external_SOURCE_DIR}/*.f")
+
+    # Create a static library from the SLATEC sources
+    add_library(slatec_lib STATIC ${SLATEC_SOURCES})
+    
+    # Set Fortran compiler flags for SLATEC (Fortran 77 compatibility)
+    target_compile_options(slatec_lib PRIVATE 
+        -std=legacy
+        -fPIC
+        -O2
+        -w  # Suppress warnings for old Fortran code
+    )
+    
+    # Link Fortran runtime
+    target_link_libraries(slatec_lib PRIVATE gfortran)
+    
+    set(SLATEC_LIBRARIES slatec_lib)
+    set(SLATEC_DOWNLOADED TRUE)
 else()
-  message(STATUS "Found QD: ${QD}")
+    message(STATUS "Found SLATEC: ${SLATEC_LIBRARY}")
+    set(SLATEC_LIBRARIES ${SLATEC_LIBRARY})
 endif()
 
-# Create a list of dependencies we need to add
-set(DEPENDENCIES_TARGETS "")
-if(DEFINED OPENBLAS_DOWNLOADED)
-  list(APPEND DEPENDENCIES_TARGETS openblas)
-endif()
-if(DEFINED SLATEC_DOWNLOADED)
-  list(APPEND DEPENDENCIES_TARGETS slatec_external)
-endif()
-if(DEFINED GSL_DOWNLOADED)
-  list(APPEND DEPENDENCIES_TARGETS gsl_external)
-endif()
-if(DEFINED QD_DOWNLOADED)
-  list(APPEND DEPENDENCIES_TARGETS qd_external)
-endif()
 
-# Set up include directories for downloaded libraries
-include_directories(${EXTERNAL_INSTALL_LOCATION}/include)
-link_directories(${EXTERNAL_INSTALL_LOCATION}/lib)
-
-# Define the library
-add_library(messlibs
-    ${PROJECT_SOURCE_DIR}/src/libmess/atom.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/io.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/limits.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/math.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/symmetry.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/d3.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/key.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/mess.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/multindex.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/units.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/graph_common.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/lapack.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/mpack.cc
-    # ${PROJECT_SOURCE_DIR}/src/libmess/mpack_dd.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/permutation.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/graph_omp.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/linpack.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/model.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/slatec.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/crossrate.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/random.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/read.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/divsur.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/dynamic.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/structure.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/configuration.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/dynlib.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/monom.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/logical.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/potential.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/system.cc
-    ${PROJECT_SOURCE_DIR}/src/libmess/trajectory.cc)
-
-# Add dependency on external libraries if needed
-if(DEPENDENCIES_TARGETS)
-  add_dependencies(messlibs ${DEPENDENCIES_TARGETS})
+# --- Other Optional Libraries ---
+find_library(QD_LIBRARIES NAMES qd libqd)
+find_package(MPI QUIET)
+
+# =============================================================================
+# Library Target (messlibs)
+# =============================================================================
+set(MESS_SOURCES
+  src/libmess/atom.cc
+  src/libmess/configuration.cc
+  src/libmess/crossrate.cc
+  src/libmess/d3.cc
+  src/libmess/divsur.cc
+  src/libmess/dynamic.cc
+  src/libmess/dynlib.cc
+  src/libmess/graph_common.cc
+  src/libmess/graph_omp.cc
+  src/libmess/io.cc
+  src/libmess/key.cc
+  src/libmess/lapack.cc
+  src/libmess/limits.cc
+  src/libmess/linpack.cc
+  src/libmess/logical.cc
+  src/libmess/math.cc
+  src/libmess/mess.cc
+  src/libmess/model.cc
+  src/libmess/monom.cc
+  src/libmess/mpack.cc
+  src/libmess/multindex.cc
+  src/libmess/permutation.cc
+  src/libmess/potential.cc
+  src/libmess/random.cc
+  src/libmess/read.cc
+  src/libmess/slatec.cc
+  src/libmess/structure.cc
+  src/libmess/symmetry.cc
+  src/libmess/system.cc
+  src/libmess/trajectory.cc
+  src/libmess/units.cc
+)
+
+add_library(messlibs STATIC ${MESS_SOURCES})
+
+# Add dependencies if they were built from source
+if(GSL_DOWNLOADED AND NOT USE_CONDA_LIBS)
+  add_dependencies(messlibs gsl_project)
 endif()
 
-# Set Fortran-compatible flags for C/C++ code
-set_target_properties(messlibs PROPERTIES
-  COMPILE_FLAGS "-fPIC -fno-strict-aliasing"
+# --- Target Properties: Include Directories ---
+target_include_directories(messlibs PUBLIC
+  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src>
+  $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src/libmess>
+  $<INSTALL_INTERFACE:include>
+  ${GSL_INCLUDE_DIRS}
 )
 
-# Set up executables
-add_executable(mess ${PROJECT_SOURCE_DIR}/src/mess_driver.cc)
-add_executable(mess-v2 ${PROJECT_SOURCE_DIR}/src/mess_test.cc)
-add_executable(messpf ${PROJECT_SOURCE_DIR}/src/partition_function.cc)
-add_executable(messabs ${PROJECT_SOURCE_DIR}/src/abstraction.cc)
-add_executable(messsym ${PROJECT_SOURCE_DIR}/src/symmetry_number.cc)
-
-# Link libraries
-target_link_libraries(mess
-    messlibs 
-    ${BLAS_LIBRARIES} 
-    ${LAPACK_LIBRARIES} 
-    ${GSL_LIBRARIES}
-    ${QD} 
-    -Wl,--start-group  # Use link groups to handle circular dependencies
-    ${SLATEC} 
-    ${FORTRAN_LIBRARIES} 
-    -lm  # Math library
-    -Wl,--end-group
-    ${CMAKE_DL_LIBS}
-)
-target_link_libraries(mess-v2
-    messlibs 
-    ${BLAS_LIBRARIES} 
-    ${LAPACK_LIBRARIES} 
-    ${GSL_LIBRARIES}
-    ${QD} 
-    -Wl,--start-group
-    ${SLATEC} 
-    ${FORTRAN_LIBRARIES} 
-    -lm
-    -Wl,--end-group
-    ${CMAKE_DL_LIBS}
-)
-target_link_libraries(messpf
-    messlibs 
-    ${BLAS_LIBRARIES} 
-    ${LAPACK_LIBRARIES} 
-    ${GSL_LIBRARIES}
-    ${QD} 
-    -Wl,--start-group
-    ${SLATEC} 
-    ${FORTRAN_LIBRARIES} 
-    -lm
-    -Wl,--end-group
-    ${CMAKE_DL_LIBS}
-)
-target_link_libraries(messabs
-    messlibs 
-    ${BLAS_LIBRARIES} 
-    ${LAPACK_LIBRARIES} 
-    ${GSL_LIBRARIES}
-    ${QD} 
-    -Wl,--start-group
-    ${SLATEC} 
-    ${FORTRAN_LIBRARIES} 
-    -lm
-    -Wl,--end-group
-    ${CMAKE_DL_LIBS}
-)
-target_link_libraries(messsym
-    messlibs 
-    ${BLAS_LIBRARIES} 
-    ${LAPACK_LIBRARIES} 
+# --- Target Properties: Compile Definitions ---
+if(USE_INT64)
+  target_compile_definitions(messlibs PUBLIC -DUSE_INT64)
+else()
+  target_compile_definitions(messlibs PUBLIC -DUSE_32BIT_INTEGERS)
+endif()
+
+# --- Target Properties: Link Libraries ---
+target_link_libraries(messlibs PUBLIC
+  ${LAPACK_LIBRARIES} # LAPACK depends on BLAS, so this is often sufficient
     ${GSL_LIBRARIES}
-    ${QD} 
-    -Wl,--start-group
-    ${SLATEC} 
-    ${FORTRAN_LIBRARIES} 
-    -lm
-    -Wl,--end-group
-    ${CMAKE_DL_LIBS}
+  ${SLATEC_LIBRARIES}
+  m dl # Common system libraries
 )
 
-install(TARGETS mess DESTINATION bin)
-install(TARGETS mess-v2 DESTINATION bin)
-install(TARGETS messpf DESTINATION bin)
-install(TARGETS messabs DESTINATION bin)
-install(TARGETS messsym DESTINATION bin)
-
-# Create a direct wrapper for missing SLATEC functions
-file(WRITE ${CMAKE_BINARY_DIR}/slatec_wrapper.f "
-      subroutine davint(x, y, n, xlo, xup, ans, ierr)
-      implicit none
-      integer n, ierr
-      double precision x(n), y(n), xlo, xup, ans
-      call davint_(x, y, n, xlo, xup, ans, ierr)
-      return
-      end
-
-      subroutine ddeabm(f, neq, t, y, tout, info, rtol, atol, idid,
-     &                 rwork, lrw, iwork, liw, rpar, ipar)
-      external f
-      integer neq, info(*), idid, lrw, iwork(*), liw
-      double precision t, y(*), tout, rtol(*), atol(*), rwork(*)
-      integer ipar(*)
-      double precision rpar(*)
-      call ddeabm_(f, neq, t, y, tout, info, rtol, atol, idid,
-     &            rwork, lrw, iwork, liw, rpar, ipar)
-      return
-      end
-
-      subroutine dbint4(x, y, n, ibcl, ibcr, fbcl, fbcr, kntopt, t, nc, 
-     &                 bc, ws, lws, ierr)
-      integer n, ibcl, ibcr, kntopt, nc, lws, ierr
-      double precision x(*), y(*), fbcl, fbcr, t(*), bc(*), ws(*)
-      call dbint4_(x, y, n, ibcl, ibcr, fbcl, fbcr, kntopt, t, nc, 
-     &            bc, ws, lws, ierr)
-      return
-      end
-
-      function dbvalu(t, a, n, k, ideriv, x, inbv, work)
-      integer n, k, ideriv, inbv
-      double precision t(*), a(*), x, work(*), dbvalu
-      dbvalu = dbvalu_(t, a, n, k, ideriv, x, inbv, work)
-      return
-      end
-")
-
-# Compile the SLATEC wrapper
-add_custom_command(
-  OUTPUT ${CMAKE_BINARY_DIR}/slatec_wrapper.o
-  COMMAND gfortran -c -O2 -fPIC ${CMAKE_BINARY_DIR}/slatec_wrapper.f -o ${CMAKE_BINARY_DIR}/slatec_wrapper.o
-  DEPENDS ${CMAKE_BINARY_DIR}/slatec_wrapper.f
-  COMMENT "Compiling SLATEC wrapper"
-)
+# --- Conditionally link optional libraries ---
+if(QD_LIBRARIES)
+    message(STATUS "Found and linking QD library: ${QD_LIBRARIES}")
+    target_link_libraries(messlibs PUBLIC ${QD_LIBRARIES})
+else()
+    message(STATUS "Optional QD library not found, skipping.")
+endif()
+
+# --- Handle MPI ---
+if(MPI_FOUND)
+  message(STATUS "MPI found, adding communication sources and linking.")
+  target_sources(messlibs PRIVATE
+    src/libmess/comm.cc
+    src/libmess/auto_comm.cc
+    src/libmess/new_comm.cc
+  )
+  target_include_directories(messlibs PUBLIC ${MPI_CXX_INCLUDE_PATH})
+  target_link_libraries(messlibs PUBLIC MPI::MPI_CXX)
+endif()
+
 
-# Create a custom target for the wrapper
-add_custom_target(slatec_wrapper DEPENDS ${CMAKE_BINARY_DIR}/slatec_wrapper.o)
-add_dependencies(messlibs slatec_wrapper)
+# =============================================================================
+# Executable Targets
+# =============================================================================
+add_executable(mess src/mess_driver.cc)
+add_executable(mess-v2 src/mess_test.cc)
+add_executable(messpf src/partition_function.cc)
+add_executable(messsym src/gumbo.cc)
+
+# Link all standard executables to the main library
+target_link_libraries(mess messlibs)
+target_link_libraries(mess-v2 messlibs)
+target_link_libraries(messpf messlibs)
+target_link_libraries(messsym messlibs)
+
+# Handle MPI executable separately
+if(MPI_FOUND)
+  add_executable(messabs src/mess_mpi.cc)
+  target_link_libraries(messabs messlibs)
+endif()
\ No newline at end of file
diff --git a/src/libmess/comm.cc b/src/libmess/comm.cc
index 3f3a949..782f415 100644
--- a/src/libmess/comm.cc
+++ b/src/libmess/comm.cc
@@ -1,9 +1,9 @@
-#include "comm.hh"
-
 //#undef INT
 
 #include <mpi.h>
 
+#include "comm.hh"
+
 void Comm::send_rate_data(const std::map<std::pair<int, int>, double>& data)
 {
   int    itemp;
diff --git a/src/libmess/lapack.cc b/src/libmess/lapack.cc
index 65f1f78..81d1e63 100644
--- a/src/libmess/lapack.cc
+++ b/src/libmess/lapack.cc
@@ -273,21 +273,8 @@ Lapack::Matrix Lapack::Matrix::operator* (Matrix m) const
 
   Matrix res(size1(), m.size2());
 
-  int_t n = size1() * m.size2();
-
-#pragma omp parallel for default(shared)  schedule(static)
-
-  for(int_t k = 0; k < n; ++k) {
-    //
-    int_t i = k / m.size2();
-
-    int_t j = k % m.size2();
-
-    res(i, j) = vdot(row(i), (ConstSlice<double>)m.column(j));
-  }
-  
-  //dgemm_('N', 'N', size1(), m.size2(), size2(), 1., 
-  //*this, size1(), m, m.size1(), 0., res, size1());
+  dgemm_('N', 'N', size1(), m.size2(), size2(), 1., 
+         *this, size1(), m, m.size1(), 0., res, size1());
 
   return res;
 }
@@ -319,13 +306,7 @@ Lapack::Vector Lapack::Matrix::operator* (const double* v) const
 
   Vector res(size1());
   
-#pragma omp parallel for default(shared)  schedule(static)
-
-  for(int_t i = 0; i < size1(); ++i)
-    //
-    res[i] = vdot(row(i), v);
-    
-  //dgemv_('N', size1(), size2(), 1.,  *this, size1(), v, 1, 0., res, 1);
+  dgemv_('N', size1(), size2(), 1.,  *this, size1(), v, 1, 0., res, 1);
   return res;
 }
 
@@ -335,13 +316,7 @@ Lapack::Vector Lapack::operator* (const double* v, Matrix m)
 
   Vector res(m.size2());
 
-#pragma omp parallel for default(shared)  schedule(static)
-
-  for(int_t i = 0; i < m.size2(); ++i)
-    //
-    res[i] = vdot(m.column(i), v);
-  
-  //dgemv_('T', m.size1(), m.size2(), 1., m, m.size1(), v, 1, 0., res, 1);
+  dgemv_('T', m.size1(), m.size2(), 1., m, m.size1(), v, 1, 0., res, 1);
   
   return res;
 }
diff --git a/src/libmess/lapack.hh b/src/libmess/lapack.hh
index 263354d..f98f246 100644
--- a/src/libmess/lapack.hh
+++ b/src/libmess/lapack.hh
@@ -25,7 +25,11 @@
 
 namespace Lapack {
 
+#ifdef USE_INT64
   typedef int64_t int_t;
+#else
+  typedef int32_t int_t;
+#endif
 
   typedef std::complex<double> complex;
 
diff --git a/src/libmess/mess.cc b/src/libmess/mess.cc
index 2ff70c5..fb31515 100644
--- a/src/libmess/mess.cc
+++ b/src/libmess/mess.cc
@@ -6654,14 +6654,12 @@ void MasterEquation::Well::_set_crm_basis ()
 
   std::vector<double> nfac;
   
-  if(with_crm_basis) {
-    //
-    _crm_basis.resize(size(), crm_size());
+  // Always initialize CRM basis when this function is called
+  _crm_basis.resize(size(), crm_size());
   
-    _crm_basis = 0.;
+  _crm_basis = 0.;
 
-    nfac.resize(crm_size());
-  }
+  nfac.resize(crm_size());
   
   _weight = 0.;
   
@@ -6673,37 +6671,35 @@ void MasterEquation::Well::_set_crm_basis ()
     
     _boltzman_sqrt[i] = std::sqrt(dtemp);
 
-    if(with_crm_basis) {
+    if(i) {
       //
-      if(i) {
-	//
-	itemp = i - 1;
-      
-	_crm_basis(i, itemp) = - _weight;
-      
-	nfac[itemp] = std::sqrt((_weight / dtemp + 1.) * _weight);
-      }
+      itemp = i - 1;
     
-      for(int r = i; r < crm_size(); ++r)
-	//
-	_crm_basis(i, r) = dtemp;
+      _crm_basis(i, itemp) = - _weight;
+    
+      nfac[itemp] = std::sqrt((_weight / dtemp + 1.) * _weight);
     }
+  
+    for(int r = i; r < crm_size(); ++r)
+      //
+      _crm_basis(i, r) = dtemp;
     
     _weight += dtemp;    
   }
 
-  if(with_crm_basis)
+  for(int r = 0; r < crm_size(); ++r) {
     //
-    for(int r = 0; r < crm_size(); ++r) {
+    itemp = r + 2;
+  
+    for(int i = 0; i < itemp; ++i)
       //
-      itemp = r + 2;
-    
-      for(int i = 0; i < itemp; ++i)
-	//
-	_crm_basis(i, r) /= nfac[r];
-    }
+      _crm_basis(i, r) /= nfac[r];
+  }
 
   _weight_sqrt = std::sqrt(_weight);
+  
+  // Set the CRM basis flag to indicate initialization is complete
+  with_crm_basis = 1;
 }
 
 MasterEquation::Well::Well (const Model::Well& model)
diff --git a/src/mess_mpi.cc b/src/mess_mpi.cc
index 5eacfdc..6d83d55 100644
--- a/src/mess_mpi.cc
+++ b/src/mess_mpi.cc
@@ -20,6 +20,9 @@
 #include <sys/resource.h>
 #include <cstdlib>
 
+//#undef INT
+#include <mpi.h>
+
 #include "libmess/mess.hh"
 #include "libmess/key.hh"
 #include "libmess/units.hh"
@@ -29,9 +32,6 @@
 #include "libmess/mpack.hh"
 #include "libmess/limits.hh"
 
-//#undef INT
-#include <mpi.h>
-
 int main (int argc, char* argv [])
 {
   const char funame [] = "master_equation: ";