Gaussian 16 Linux 📍

#!/bin/bash for input in *.gjf; do base=$input%.gjf echo "Running $base at $(date)" >> job.log # Run with 4 cores, save unique log g16 -p=4 $input $base.log # Check for convergence if grep -q "Normal termination" $base.log; then echo "SUCCESS: $base" >> job.log # Extract final SCF energy grep "SCF Done" $base.log | tail -1 >> energies.txt else echo "FAILED: $base" >> job.log fi done Extract Gibbs free energy from a frequency job:

#!/bin/bash #SBATCH --job-name=G16_HF #SBATCH --nodes=1 #SBATCH --ntasks-per-node=16 #SBATCH --mem=64G #SBATCH --time=24:00:00 export GAUSS_SCRDIR=/local/scratch/$SLURM_JOB_ID mkdir -p $GAUSS_SCRDIR Run Gaussian with OpenMPI hybrid g16 < input.com > output.log Clean up rm -rf $GAUSS_SCRDIR Benchmarks: Tuning Gaussian 16 on Linux Raw installation is not enough. You must optimize for your hardware. Memory Tuning In your input file, do not allocate all RAM ( %Mem=64GB ) if you run parallel jobs. The rule of thumb: %Mem = (Total RAM / Number of cores) * 0.8 (leave 20% for OS overhead). Linux Kernel Parameters For heavy DFT calculations (e.g., B3LYP/def2-TZVPP on 100 atoms), tune the swappiness and I/O scheduler:

sudo mount -t tmpfs -o size=30G tmpfs /mnt/ramdisk export GAUSS_SCRDIR=/mnt/ramdisk Warning: Compute-intensive jobs like CCSD(T) can exceed this. Monitor df -h /mnt/ramdisk live. Even seasoned users encounter errors unique to the Gaussian 16 Linux ecosystem. 1. "Cannot open shared object file: libcuda.so.1" Cause: Gaussian tries GPU acceleration but CUDA is missing. Fix: Disable GPU in input: %GPUCPU=0 or use %NoGPU . 2. Segmentation Fault (core dumped) Cause: Stack limit too low on Linux. Fix: Run ulimit -s unlimited before launching Gaussian. Add to your .bashrc . 3. Linda Workers Keep Disconnecting Cause: Firewall blocks ports or SSH key authentication fails. Fix: Ensure passwordless SSH between nodes and open dynamic ports (e.g., 60000-61000) in iptables . Advanced Scripting: Automating Gaussian 16 on Linux Linux excels at batch processing. Here is a bash script to run a series of single-point energies on all .gjf files in a folder: gaussian 16 linux

sudo apt update && sudo apt install libc6 libstdc++6 libopenmpi-dev openmpi-bin For RHEL/Fedora:

sudo nano /etc/profile.d/gaussian.sh Add: The rule of thumb: %Mem = (Total RAM / Number of cores) * 0

# Reduce swapping echo 10 > /proc/sys/vm/swappiness # Use 'none' or 'noop' scheduler for NVMe scratch disks echo noop > /sys/block/nvme0n1/queue/scheduler If you have abundant RAM, put GAUSS_SCRDIR in RAM:

cd /opt/gaussian/g16 ./bsd/install.csh Choose option 5 (Linux x86_64) and select your parallel flavor: SMP (single node) or Linda (multi-node). The Gaussian input file ( test.com ) remains platform-agnostic, but the submission method differs drastically on Linux. Interactive Test (Single Core) g16 < test.com > test.log Parallel Execution (SMP – Shared Memory) Always specify %NProcShared and %Mem . Even seasoned users encounter errors unique to the

Gaussian 16 remains the gold standard for electronic structure modeling. While the software runs on multiple platforms, its true power—scalability, speed, and flexibility—unfolds only on Linux . Whether you are a PhD student setting up your first calculation or a system administrator maintaining a high-performance computing (HPC) cluster, understanding the nuances of running Gaussian 16 on Linux is essential.