These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.15 s (backtrack: 0/20).

[ebuild  N     ] sci-libs/fftw-3.3.10-r1:3.0/3::gentoo  USE="openmp threads -doc -fortran -mpi -test (-zbus)" CPU_FLAGS_X86="avx avx2 fma3 sse sse2 -fma4" 4047 KiB
[ebuild  N     ] sci-libs/lmfit-9.0-r1:0/9::gentoo  36 KiB
[ebuild  N     ] dev-cpp/muParser-2.3.5:0/2.3::gentoo  USE="openmp -doc -test" 113 KiB
[ebuild  N     ] x11-libs/libpciaccess-0.19::gentoo  USE="zlib -static-libs" 64 KiB
[ebuild  N     ] sys-apps/hwloc-2.12.2:0/15::gentoo  USE="X cairo cpuid pci -cuda -debug -doc -l0 -nvml -rocm (-selinux) -static-libs -svg -udev -valgrind -xml" VIDEO_CARDS="-nvidia" 5504 KiB
[ebuild  N     ] sci-chemistry/gromacs-2023.5:0/2023.5::gentoo  USE="custom-cflags doc fftw gmxapi gmxapi-legacy hwloc offensive openmp single-precision threads tng -blas -build-manual -clang -clang-cuda -cuda -double-precision -lapack -mkl -mpi -opencl (-python) -test" CPU_FLAGS_X86="avx avx2 avx512f sse2 sse4_1 -fma4" PYTHON_SINGLE_TARGET="python3_14 -python3_12 -python3_13" 54354 KiB

Total: 6 packages (6 new), Size of downloads: 64117 KiB