[gmx-users] Regarding precision in gromacs

[Dilip H N]

Hello,
i have installed gromacs 2016.2, and in the command line if i type gmx
--version i am getting as:-
GROMACS version:    2016.2
Precision:          single
Memory model:       64 bit
MPI library:        thread_mpi
OpenMP support:     enabled (GMX_OPENMP_MAX_THREADS = 32)
GPU support:        disabled
SIMD instructions:  AVX2_256
FFT library:        fftw-3.3.3-sse2-avx
RDTSCP usage:       enabled
TNG support:        enabled
Hwloc support:      disabled
Tracing support:    disabled
Built on:           Sun Jul 16 13:28:27 IST 2017
Built by:           root at DILIP [CMAKE]
Build OS/arch:      Linux 3.13.0-24-generic x86_64
Build CPU vendor:   Intel
Build CPU brand:    Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
Build CPU family:   6   Model: 60   Stepping: 3
Build CPU features: aes apic avx avx2 clfsh cmov cx8 cx16 f16c fma htt lahf
mmx msr nonstop_tsc pcid pclmuldq pdcm pdpe1gb popcnt pse rdrnd rdtscp sse2
sse3 sse4.1 sse4.2 ssse3 tdt x2apic
C compiler:         /usr/bin/gcc GNU 4.8.4
C compiler flags:    -march=core-avx2     -O3 -DNDEBUG -funroll-all-loops
-fexcess-precision=fast
C++ compiler:       /usr/bin/c++ GNU 4.8.4
C++ compiler flags:  -march=core-avx2    -std=c++0x   -O3 -DNDEBUG
-funroll-all-loops -fexcess-precision=fast

My doubt is tht how does the precision have any effect on the
simulation..?? and how can i convert/make the gromacs version tht i have
installed(2016.2), from single precision to double precision...?? what are
the commands tht i need to give ...??

Thank you...
-- 
With Best Regards,

DILIP.H.N
Ph.D Student