LongRangeCorrectionLJ

Long-range correction of the Lennard-Jones interaction

The long-range correction of the Lennard-Jones interaction between the solute and solvent can be computed in ERmod.
To enable this computation, it is enough to set ljlrc = 'yes' in parameters_fe as of ver 0.3.5
and it is necessary to follow the procedures described below in this page when the version is 0.3.4 or earlier.

When ljlrc = 'yes' is set in parameters_fe, it is also necessary to set the average volume of the system to avevolume.
When the system is large enough, it has only a negligible effect on the computed result whether the avevolume value is taken from the reference solvent or from solution.
parameters_fe is then read, for example, as

::::sh
  ....
 ljlrc = 'yes'
 avevolume = 0.14752840E+05
  ....

The unit of avevolume is Angstrom^3; note that it not be given in nm^3.
When avevolume is not set in parameters_fe, user is asked

::::sh
  What is the average volume of reference solvent? (in Angstrom^3)

and is to type the average volume in Angstrom^3 directly on terminal.

Caution: The Lennard-Jones long-range correction scheme can be used only when the solvent distribution is homogeneous (radial distribution function is essentially unity) when the solvent molecule is separated beyond the Lennard-Jones cutoff distance in any direction from any atom in the solute molecule. The correction scheme may not be applied when the solute and/or solvent molecule is comparable in size to or larger than the cutoff radius, which is typically ~10 Angstrom, or when the solvent is inhomogeneous in nanoscale and, for example, is micelle or lipid membrane.

When the version of ERmod is 0.3.4 or earlier, the following procedures are necessary.
In the parent directory of the distributed ERmod package, there is a sub-directory extensions/LJLRC.
The modifed slvfe.F90 program contained in this sub-directory can evaluate the long-range correction.
The slvfe.F90 program contained in the extensions/LJLRC directory has a key of ljlrc, which enables the Lennard-Jones long-range correction at ljlrc = 'yes'.
To use the slvfe.F90 program contained in this directory, user simply does the followings in the parent directory of ERmod.

::::sh
mv slvfe.F90 slvfe_original.F90
cp extensions/LJLRC/slvfe.F90 ./
make
make install

Without stating ljlrc = 'yes' in parameters_fe, the modified slvfe works just as in the same way as the original slvfe.
The difference between the original and modified slvfe.F90 is written in the diff_slvfe file in the extensions/LJLRC directory.
By setting ljlrc = 'yes' in parameters_fe, user is required to prepare a volumedata file which contains the average volume of the system.
volumedata is read, for example, as

::::sh
cat volumedata
30106.4

If the volumedata file is not present, user is asked

::::sh
  What is the average volume of reference solvent? (in Angstrom^3)

and is to type the average volume in Angstrom^3 directly on terminal.