RELENE

Brian T. Luke, Ph.D.

[email protected]

In many computational investigations using Gaussian9x, I have needed to compare the relative energies of different isomers of the same compound. This required me to combine the internal and zero-point vibrational energies (ZPE) of each isomer, take differences, and multiply the this difference by 627.509 to get the relative energies in kcal/mol. To make this process easier, I've written RELENE.

RELENE is a simple interactive program that asks you for the required information and does all of the necessary work for you. This program certainly isn't rocket science, but it is a handy little tool that I use regularly.
Obtaining RELENE
To download RELENE, simply hold down the [Shift] key and click on relene.tar.gz.
Installing RELENE
To install RELENE, simply move this compressed tar file to a new directory and enter the commands 

     gunzip relene.tar
     tar -xvf relene.tar
If gunzip is not installed on your system, please consult Installing and Running gzip/gunzip. When this file is untarred, four files will be extracted. The names of these files and their contents are listed below.

File Contents
RELENE This is the executable program (if not executable use the command chmod +x RELENE).
test.inp A sample input stream for the program.
test.out The resulting output stream generated by RELENE from test.inp.
readme.1st A small note reminding you how to run RELENE.

Now that you have unloaded RELENE to your system, here is all you need to do to run the program.

Either make sure that the directory containing RELENE is in your PATH, or move RELENE to a directory in your current path.

Let's say, for example, you have the energy and zero-point vibrational energy (ZPE) of three different compounds. You will run the program by issuing the command 


	  RELENE
The program would first ask you 

	  HOW MANY CONFORMATIONS ARE THERE?
and you would respond with 

	  3
The program then gives you the following prompt: 

	  ENERGY AND ZPE OF CONFORMATION  1
and you (for example) would respond with 

	  -120.34427 0.01277
The program then asks 

	  ENERGY AND ZPE OF CONFORMATION  2
and you would enter 

	  -120.34272 0.01249
Finally, the program asks 

	  ENERGY AND ZPE OF CONFORMATION  3
and you would enter 

	  -120.34905 0.01318
The program then responds with 

	  1  -120.33150    2.7
	  2  -120.33023    3.5
	  3  -120.33587     .0
The first column lists the conformation number, the second gives the combined internal and (unscaled) vibrational energy in hartrees, and the third gives the relative energies of these compounds in kcal/mol.

The program then prompts you for another set of conformations: 


	  HOW MANY CONFORMATIONS ARE THERE?
To exit the program, you simply respond with 

	  0

To avoid typographical errors, which would necessitate re-entering all of the data, you can place all of the input into a file. The required input for this example is contained in the file "test.inp": 


	  3
	  -120.34427 0.01277
	  -120.34272 0.01249
	  -120.34905 0.01318
	  0

You can then run the program by entering the command 


	  RELENE < test.inp > test.ene

All screen writes would be written to "test.ene", and this file would contain the following information. 


	  HOW MANY CONFORMATIONS ARE THERE?
	  ENERGY AND ZPE OF CONFORMATION  1
	  ENERGY AND ZPE OF CONFORMATION  2
	  ENERGY AND ZPE OF CONFORMATION  3
	  1  -120.33150    2.7
	  2  -120.33023    3.5
	  3  -120.33587     .0
	  HOW MANY CONFORMATIONS ARE THERE?

This data is contained in the file "test.out", and you can make sure that the program worked correctly by issuing the command 


	  diff test.ene test.out
There should be no difference in these files.

Please note that if you are calculating relative energies of isomers and the internal energy already includes the ZPE (i.e. if you are using G2 energies or the results of some other compound procedure), you simply enter a ZPE of 0.0.

I hope this simple program makes your life a little easier.

Disclaimer
Please note that this free package is distributed "as is" and comes with no explicit or implicit warranties. The program author is to be held blameless for any actions that occur while running the package.

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� 1999 Brian T. Luke, Ph.D.