Per-residue energy decompositions in NAMD
** 原文地址 之前一篇文章中，通过计算范德华和静电相互作用，发现amber和namd的计算结果一致。在本文中，将通过namd来对轨迹进行分析，将范德华和静电相互作用分解到受体的每一个残基上，方法相当于将受体分解为单个的残基pdb，分别计算之后再加和。当然，这完全可以由amber的相应模块实现。此处贴出本文章，主要是认为这种实现方式很有趣，如果让我来做的话，我该是要扑街了。 Calculate Decompositions Using Namd **
The following script uses vmd to create pdb files. Each atom is
labeled with a 0 (excluded), 1(species #1) or 2(species #2) in beta
column. namd will compute the interaction energy between species #1 and
#2. A separate pdb file is created for each residue (species #2). The
ligand is always species #1. We are using amber inputs in this example.
The namd input file loops over each pdb file to compute the interaction
energy for every timestep. run.005.vmd.namd.energy.decomp_sw.csh:
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135#! /bin/csh -fe
set mountdir = "/nfs/user03/chembio/AMBER_Project"
set start = 1
set stop = 35
set offset = 1
set workdir = "${mountdir}/006.FP.VMD.NAMD"
cd ${workdir}
###########################################
set res_start = ${start}
set res_stop = ${stop}
@ loop_stop = ${res_stop} + 1
cat << EOF > ptraj.in
trajin ${mountdir}/004.ptraj/1qp6.rec.trj.stripfit
trajout 1qp6.rec.stripfit.dcd charmm
EOF
ptraj ${mountdir}/002.TLEAP/1qp6.rec.gas.leap.prm7 ptraj.in > ptraj.out
###########################################
cat <<EOFK >pair.maker.tcl
#opens the file that has the atoms that are to be set-up for pair-interaction calculations
mol load parm7 ${mountdir}/002.TLEAP/1qp6.rec.gas.leap.prm7 rst7 ${mountdir}/002.TLEAP/1qp6.rec.gas.leap.rst7
for {set resid_num $res_start} {\$resid_num < $loop_stop} {incr resid_num} {
set all [atomselect top all]
\$all set beta 0
set case1 [atomselect top "protein and resid 36 to 70"]
\$case1 set beta 1
set case2 [atomselect top "protein and resid \$resid_num"]
\$case2 set beta 2
\$all writepdb 1qp6.rec.gas.pair.\$resid_num.pdb
}
quit
EOFK
###########################################
# copy DCD files required in the calculations
# to the current directory
# make a special PDB files defining what the two species will be for pair interaciton calcs
/nfs/user05/lingling/zzz.programs/vmd-1.9.1/bin/vmd -dispdev text -e pair.maker.tcl >> zzz.pair.maker.out
echo "MAKE INPUT FILES"
date
set res_start = ${start}
set res_stop = ${stop}
@ loop_stop = ${res_stop} + 1
set start_residue = $res_start
set loop_stop = $loop_stop
set count01 = $start_residue
###########################################
###########################################
while ( $count01 < $loop_stop )
###########################################
cat <<EOFL >07_to_08pr.$count01.in
# initial config
temperature 0
# output params
outputname 1qp6.rec.gas.$count01
binaryoutput no
# integrator params
timestep 1.0
# force field params
amber on
parmfile ${mountdir}/002.TLEAP/1qp6.rec.gas.leap.prm7
ambercoor ${mountdir}/002.TLEAP/1qp6.rec.gas.leap.rst7
readexclusions yes # exclusions are taken from parmfile
exclude scaled1-4
1-4scaling 0.833333 # =1/1.2, default is 1.0
scnb 2.0 # Default
switching off
cutoff 999.0
# Atoms in group 1 have a 1 in the B column; group 2 has a 2
pairInteraction on
pairInteractionFile 1qp6.rec.gas.pair.$count01.pdb
pairInteractionCol B
pairInteractionGroup1 1
pairInteractionGroup2 2
# First frame saved was frame 1000.
set ts 1000
coorfile open dcd 1qp6.rec.stripfit.dcd
# Read all frames until nonzero is returned.
while { ![coorfile read] } {
# Set firstTimestep so our energy output has the correct TS.
firstTimestep \$ts
# Compute energies and forces, but don't try to move the atoms.
run 0
incr ts 1000
}
coorfile close
EOFL
###########################################
cat << EOF > fp.namd.${count01}.csh
#! /bin/csh
#PBS -l walltime=24:00:00
#PBS -V
cd ${workdir}
hostname
date
echo "START CALCS"
/nfs/user03/fochtman/zzz.programs/NAMD_2.9_Source/Linux-x86_64-g++/namd2 07_to_08pr.${count01}.in > 07_to_08pr.${count01}.out
EOF
qsub fp.namd.${count01}.csh
@ count01 = $count01 + 1
###########################################
###########################################
end
exit
** Energy Decomposition Analysis **
This script using awk to calculate the mean and standard deviation.
run.006.vmd.namd.energy.decomp_sw_analysis.csh: 1
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37#! /bin/csh -fe
set mountdir = "/nfs/user03/chembio/AMBER_Project"
set start = 1
set stop = 35
set offset = 1
set workdir = "${mountdir}/006.FP.VMD.NAMD"
cd ${workdir}
set res_start = ${start}
set res_stop = ${stop}
@ loop_stop = ${res_stop} + 1
set start_residue = $res_start
set loop_stop = $loop_stop
set count01 = $start_residue
echo "resid,mean,std" > vdw.fp.output.csv
echo "resid,mean,std" > es.fp.output.csv
###########################################
while ( $count01 < $loop_stop )
## Gets VDW
awk ' BEGIN{count=0;sum=0;sum2=0;} /^ENERGY:/{count=count+1;sum=sum+$8;sum2 = sum2 + $8^2} END{mean=sum/count; std= ((sum2/count)- (mean^2))^(1/2); print "'${count01}'," mean "," std } ' 07_to_08pr.${count01}.out >> vdw.fp.output.csv
##Get ES
awk ' BEGIN{count=0;sum=0;sum2=0;} /^ENERGY:/{count=count+1;sum=sum+$7;sum2 = sum2 + $7^2} END{mean=sum/count; std= ((sum2/count)- (mean^2))^(1/2); print "'${count01}'," mean "," std } ' 07_to_08pr.${count01}.out >> es.fp.output.csv
@ count01 = $count01 + 1
end # while
exit