Zz376 at 13:58, 1 March 2022

2022-03-01T13:58:17Z

← Older revision		Revision as of 13:58, 1 March 2022
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	= Running GAMESS =		= Running GAMESS =
			== Set up running script ==
	After a successful compilation and linking, you should see the script <code>./rungms</code> appear in the GAMESS root directory. You need to edit this file, specifically the first four lines after the comments. You should create two directories, <code>restart</code> and <code>userscr</code>, and point the script to them, and also set <code>GMSPATH</code> to the actual installation location.		After a successful compilation and linking, you should see the script <code>./rungms</code> appear in the GAMESS root directory. You need to edit this file, specifically the first four lines after the comments. You should create two directories, <code>restart</code> and <code>userscr</code>, and point the script to them, and also set <code>GMSPATH</code> to the actual installation location.

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	where <code>00</code> is the version number you'll have specified in the configuration stage, and the three 1's are to do with parallelisation options, here we run the most basic serial version.		where <code>00</code> is the version number you'll have specified in the configuration stage, and the three 1's are to do with parallelisation options, here we run the most basic serial version.

			== Input file ==
	You can find example input files under <code>./tests/</code>, and the complete documentation [https://www.msg.chem.iastate.edu/gamess/GAMESS_Manual/docs-input.txt here].		You can find example input files under <code>./tests/</code>, and the complete documentation [https://www.msg.chem.iastate.edu/gamess/GAMESS_Manual/docs-input.txt here].

			=== Geometry ===
	The default geometry specification is by only specifying symmetrically unique atoms, but you can also use cartesian and Z matrix format. This is controlled by a <code>$contrl</code> group keyword.		The default geometry specification is by only specifying symmetrically unique atoms, but you can also use cartesian and Z matrix format. This is controlled by a <code>$contrl</code> group keyword.

			Documentation on point group symmetry can be found by searching <code>point group</code> in the documentation. Briefly, C2v is <code>cnv 2</code> and D_infh, despite their advice to use <code>dnh 4</code>, you should use <code>dnh 2</code>, otherwise results won't agree with other packages.

			=== Consistency with other packages ===
	GAMESS also freezes core electrons in post-HF methods by default, and this may lead to slightly different results compared to other programmes. To turn it off in coupled-cluster for example, add the <code>ncore=0</code> keyword in the <code>$CCINP</code> group.		GAMESS also freezes core electrons in post-HF methods by default, and this may lead to slightly different results compared to other programmes. To turn it off in coupled-cluster for example, add the <code>ncore=0</code> keyword in the <code>$CCINP</code> group.

			=== Basis sets ===
	GAMESS doesn't use standard basis names, to find out the internal names, search <code>$BASIS</code> in the documentation above. Specifically, it doesn't have a lot of the def2 family of basis sets. You can paste the basis sets into the input file from [https://www.basissetexchange.org/ Basis Set Exchange], but this requires that you use their own geometry specification standards (symmetrically unique atoms).		GAMESS doesn't use standard basis names, to find out the internal names, search <code>$BASIS</code> in the documentation above. Specifically, it doesn't have a lot of the def2 family of basis sets. You can paste the basis sets into the input file from [https://www.basissetexchange.org/ Basis Set Exchange], but this requires that you use their own geometry specification standards (symmetrically unique atoms).

			=== Sample input file ====
	Finally, an example input for a water molecule at 1.6 A bond length and 104.45 bond angle with a restricted HF reference at cc-pVDZ/CR-CCSD(T) level is given below:		Finally, an example input for a water molecule at 1.6 A bond length and 104.45 bond angle with a restricted HF reference at cc-pVDZ/CR-CCSD(T) level is given below:
	<pre>		<pre>

Zz376: Create GAMESS page

2022-03-01T13:50:49Z

Create GAMESS page

New page

= Obtaining GAMESS =
You can request for the latest version of GAMESS for free [https://www.msg.chem.iastate.edu/gamess/download.html here].

= Compilation =
GAMESS has an unusual but straightforward system for compiling: untar the archive and run the <code>./configure</code> script, and answer all the questions. For the most basic installation, choose <code>socket</code> for the parallelisation. The script will ask if you want to install a number of packages, and they are all completely optional.

After the configuration, do '''not''' follow <code>machines/readme.unix</code> but instead follow the instructions in <code>./README.md</code>, i.e., run <code>make ddi</code>, <code>make modules</code> (if not using libxc), and then <code>make -j${nproc}</code>.

= Running GAMESS =
After a successful compilation and linking, you should see the script <code>./rungms</code> appear in the GAMESS root directory. You need to edit this file, specifically the first four lines after the comments. You should create two directories, <code>restart</code> and <code>userscr</code>, and point the script to them, and also set <code>GMSPATH</code> to the actual installation location.

After all this, you can run GAMESS by invoking
<pre>
rungms [input_file] 00 1 1 1
</pre>
where <code>00</code> is the version number you'll have specified in the configuration stage, and the three 1's are to do with parallelisation options, here we run the most basic serial version.

You can find example input files under <code>./tests/</code>, and the complete documentation [https://www.msg.chem.iastate.edu/gamess/GAMESS_Manual/docs-input.txt here].

The default geometry specification is by only specifying symmetrically unique atoms, but you can also use cartesian and Z matrix format. This is controlled by a <code>$contrl</code> group keyword.

GAMESS also freezes core electrons in post-HF methods by default, and this may lead to slightly different results compared to other programmes. To turn it off in coupled-cluster for example, add the <code>ncore=0</code> keyword in the <code>$CCINP</code> group.

GAMESS doesn't use standard basis names, to find out the internal names, search <code>$BASIS</code> in the documentation above. Specifically, it doesn't have a lot of the def2 family of basis sets. You can paste the basis sets into the input file from [https://www.basissetexchange.org/ Basis Set Exchange], but this requires that you use their own geometry specification standards (symmetrically unique atoms).

Finally, an example input for a water molecule at 1.6 A bond length and 104.45 bond angle with a restricted HF reference at cc-pVDZ/CR-CCSD(T) level is given below:
<pre>
$contrl scftyp=rhf coord=zmt runtyp=energy units=angs cctyp=cr-cc ispher=1 $end
$system mwords=100 memddi=500 $end
$guess guess=huckel $end
$ccinp maxcc=100 ncore=0 $end
$basis gbasis=ccd $end
$data

cnv 2

O
H 1 1.6
H 1 1.6 2 104.45
$end
</pre>
All keywords are case insensitive. Note the single whitespace in front of each keyword group, which seems to be important..

= Issues with its coupled cluster modules =
GAMESS implements a great variety of coupled cluster methods, including the renormalised and the completely renormalised CCSD(T) and [T]. The reference paper for all of these methods (CCSD, CCSD(T)/[T], (C)RCCSD(T)/[T]) is found [https://doi.org/10.1016/S0010-4655(02)00598-2 here]. Unfortunately if you ever tried to code these equations up from scratch yourself, you'll find that they're wrong. After extensive debugging, we found that there are two typos in Table 1 defining the intermediates needed in the CCSD amplitude update equations:

[[File:Piecuch_ccsd_typo.png]]

GAMESS - Revision history

Zz376 at 13:58, 1 March 2022

Zz376: Create GAMESS page