#!/bin/bash

# Set some environment variables 
FREE_ENERGY=`pwd`
echo "Free energy home directory set to $FREE_ENERGY"
MDP=$FREE_ENERGY/MDP
echo ".mdp files are stored in $MDP"

# Change to the location of your GROMACS-2018 installation
GMX=/usr/local/gromacs/bin

for (( i=0; i<31; i++ ))
do
    lambda=$i
    prevlambda="$(($i - 1))"

    # A new directory will be created for each value of lambda and
    # at each step in the workflow for maximum organization.

    mkdir Lambda_$lambda
    cd Lambda_$lambda

    coorfile=$FREE_ENERGY/etoh_solv.gro
    if [[ $i -gt 1 ]]; then
        coorfile=$FREE_ENERGY/Lambda_$prevlambda/Production_MD/md$prevlambda.gro
    fi

    ##############################
    # ENERGY MINIMIZATION STEEP  #
    ##############################
    echo "Starting minimization for lambda = $lambda..." 

    mkdir EM
    cd EM

    # Iterative calls to grompp and mdrun to run the simulations

    $GMX/gmx grompp -f $MDP/em_steep_$lambda.mdp -c $coorfile -p $FREE_ENERGY/topol.top -o min$lambda.tpr

    $GMX/gmx mdrun -deffnm min$lambda

    sleep 10

    #####################
    # NVT EQUILIBRATION #
    #####################
    echo "Starting constant volume equilibration..."

    cd ../
    mkdir NVT
    cd NVT

    $GMX/gmx grompp -f $MDP/nvt_$lambda.mdp -c ../EM/min$lambda.gro -p $FREE_ENERGY/topol.top -o nvt$lambda.tpr

    $GMX/gmx mdrun -deffnm nvt$lambda

    echo "Constant volume equilibration complete."

    sleep 10

    #####################
    # NPT EQUILIBRATION #
    #####################
    echo "Starting constant pressure equilibration..."

    cd ../
    mkdir NPT
    cd NPT

    $GMX/gmx grompp -f $MDP/npt_$lambda.mdp -c ../NVT/nvt$lambda.gro -p $FREE_ENERGY/topol.top -t ../NVT/nvt$lambda.cpt -o npt$lambda.tpr

    $GMX/gmx mdrun -deffnm npt$lambda

    echo "Constant pressure equilibration complete."

    sleep 10

    #################
    # PRODUCTION MD #
    #################
    echo "Starting production MD simulation..."

    cd ../
    mkdir Production_MD
    cd Production_MD

    $GMX/gmx grompp -f $MDP/md_$lambda.mdp -c ../NPT/npt$lambda.gro -p $FREE_ENERGY/topol.top -t ../NPT/npt$lambda.cpt -o md$lambda.tpr

    $GMX/gmx mdrun -deffnm md$lambda

    echo "Production MD complete."

    # End
    echo "Ending. Job completed for lambda = $lambda"

    cd $FREE_ENERGY
done

exit;