General | Licensing | Installation | Input | Performance | Execution


Q. What is the relationship between GAMESS-US and GAMESS-UK?

A. GAMESS-UK and GAMESS-US are two quite separate programs. Historically GAMESS-UK was developed from the original Gamess program distributed by QCPE (1981). During the last 20 years the UK version has been substantially modified and improved, with the developments conducted quite separately from the work at Iowa. The two programs share a common source (the original QCPE version).

Further details on the present and planned functionality for GAMESS-UK are available from the GAMESS-UK homepage.

Major Differences in Functionality.

  1. Version 6 of GAMESS-UK includes Density functional capabilities,
    • Energies and gradients for closed and open shells (UKS)
    • B3LYP, BLYP, BP86, BP91, HCTH, B97, B97-1 and LDA functionals
    • fitted coulomb integrals (Dunlap) for efficiency
  2. GAMESS-UK has more extensive and efficient post Hartree Fock capabilities than GAMESS-US. These include;
    • the MULTI MCSCF code (werner Knowles),
    • both direct-CI (van Lenthe and Saunders) and conventional, table-driven MRDCI (with selection, Buenker and Peyerimhoff)
    • CCSD and CCSD(T), plus Full-CI
    • spin natural orbitals from CI wavefunctions, allowing ESR spin property evaluation
    • RPA and MCLR (multi-configuration linear response) capabilities
    • OVGF and TDA techniques for treating ionisation processes.
  3. MP2 gradients and analytic frequencies for both closed and open shells are present in GAMESS-UK. Multi-Reference MP2 (CAS-PT2) is also available in Version 6.2 of GAMESS-UK.
  4. Both have a wide range of properties, with Raman intensities available in GAMESS-UK.
  5. In addition to the SCRF and PCM treatments of solvation, GAMESS-UK (Version 6.2) has the DRF method for solvation and embedding (due to P. van Duijnen).
  6. The ZORA Relativistic Approximation is available in Version 6.2 of GAMESS-UK.
  7. The parallel version of GAMESS-UK is arguably more efficient and, based on the Global Array Tools from PNNL, is probably more open-ended. The UK variant contains MP2-gradients and SCF analytic 2nd derivatives, neither available in the US version.

Support Arrangements, Licencing and Costs

  • GAMESS-US is completely free, while GAMESS-UK has an associated cost for users that are not UK academics; this is set to a nominal rate for academics. All income received is spent in the on-going support and development of the code. A full time support position at Daresbury ensures that users receive new versions when these are released, and provides the mechanism for dealing with users problems.

Q. Is a Graphical User Interface available to run GAMESS-UK?

A. A number of developments to provide graphical front end capabilities designed to facilitate usage of the code have been undertaken. These include:

  • A graphical user interface to the GAMESS-UK has been developed as part of the CCP1GUI project. More information on the CCP1GUI and it's interface to GAMESS-UK can be found on the CCP1GUI website.
  • Using MOLDEN to prepare Z-matrices and to start simple interactive jobs. At present MOLDEN can process data from the GAMESS-UK output file, displaying optimised structures, orbitals and frequencies.

Q. Where is the GAMESS-UK User's Manual?

A. A searchable cop of the GAMESS-UK manual can be found online by clicking on the following link: GAMESS-UK User's Manual.

Q. Is there any on-line training available?

A. The slides from various tutorials that we have given are available online.

Q. I am interested in performing QM/MM calculations, and have heard that GAMESS-UK is now interfaced to the Charmm code. Where can I find out more?

A. Take a look at the CHMGUK: CHARMM-GAMESS-UK for more details.


Q. Do I have to use an official GAMESS-UK Licence to obtain the code? What is the procedure? What is the Cost?

A. There are several types of GAMESS-UK licences issued by CFS, including Academic, Joint Software Development (JSDL), Super-computer Centre, and Industrial Licences; the licencing conditions are generally governed by the nature of the requesting organisation. The standard academic licence provides the GAMESS-UK binary, a manual and software support and updates for the duration of the licence (generally 3 years).

All licences are free for academic users in the UK. There is an associated cost for academic users outside the UK, although this is set at a nominal level.

There are free demo binaries available for Linux, Mac OSX and Windows. The demo binaries support the full functionality of the code, but are restricted to systems with fewer than 250 basis functions.

All income received is spent in the on-going support and development of the code. A full time support position at Daresbury ensures that users receive new versions when these are released, and provides the mechanism for dealing with users problems.

Copies of the licences are available on the WWW at:, but we would ask that all potential users first send an email to, before downloading a licence.

Q. Is the source code for GAMESS-UK available?

A. The source code is provided through a Joint Software Development Licence (JSDL). There is no additional cost over that identified above. Copies of the JSDL are available by sending an email to

Q. How is the GAMESS-UK program shipped?

A. GAMESS-UK is usually made available for download via ftp, although copies can also be made available on CD-ROM. Customers who wish to have GAMESS-UK ftp'd to their machines should create a local account for GAMESS-UK technical support staff to download the software to.


Installing GAMESS-UK

Q. I've downloaded the installer for Windows, but when I try and run it I get the following error:

This advertised application will not be installed because it might be unsafe. Contact your administrator to change the installation user interface option of the package to basic/

A. This appears to be a permissions problem. You can cure it by running the windows installer at a lower user interface level. Open a command prompt and cd to the directory containing the installer. Then execute the command:

msiexec /qb /I GAMESS-UK-Setup.msi



Q. I have manually created a new GAMESS-UK input file based on one of the files from the samples directory, but when I run it I get an unrecognised directive error. What is wrong?

A. The most common problem used to be the existence of tab stops in your input file. The input parser historically had problems on tab stops. This problem has been cured in Version 6.2 of the code.

Q. I have always kept old input data after the ENTER directive, believing that ENTER acted as the final input line to be processed. Now when I do that, I end up with a program error. What has changed?

A. GAMESS-UK now handles multiple RUNTYPEs within a given job, so that ENTER only acts as the input data terminator for the step currently being processed. The code will view lines presented after the first ENTER directive as being data for a second RUNTYPE, and will fail if those lines are not relevant to this modus operandi.



Q. I am interested in studying biomolecular systems using ab initio methods, but my present software is extremely slow after around 50-100 atoms. Can GAMESS-UK really handle these big jobs?

A. CFS Inc. support a number of users who routinely using the GAMESS-UK program to investigate large systems - the largest benchmark we have done to date (part of a pocket of the HIV virus) involved 291 atoms and 2984 basis functions. SCF and DFT Calculations on systems involving 150+ atoms are fairly routine on commodity clusters with, say, 16-32 IA32 CPUs.

Q. Is GAMESS-UK only really any good for large jobs on big very expensive machines. I have a Pentium PC and an SGI O2 workstation, so GAMESS-UK probably won't be able to run any realistic calculations, will it?

A. On the contrary, all of the functionality within GAMESS-UK will be accessible on such machines. The minimum requirement for running the code is 64 MByte RAM and 2 GB of disk - less than that, however, and you will find that the scope of application with the GAMESS-UK program will be limited.



Q. How do I submit a GAMESS-UK job on a parallel machine?

A. Take a look at the at the appropriate section of the User Manual, Part 14. GAMESS-UK Parallel Implementations. If you are still uncertain how to proceed, please send an e-mail to GAMESS support with a description of your machine and the associated environment.

Q. When I attempt to execute the validation script in the examples directory, examples/chap12, I find the response rungamess: Command not found, even though the rungamess script is in its correct place.

A. If the system you are running on does not support ksh, you will need to edit the first line of the rungamess script to reference a replacement, e.g. on Linux, you can use /bin/bash

Q. When I attempt to execute GAMESS-UK using the rungamess script, I find that attempting to use the Table-Ci module produces the error, 0: GAMESS-UK Error: i/o error; file = table, even when the Table data base is present in the GAMESS-UK/libs directory. What is wrong?

A. This arises because of a limit in the number of characters that may constitute the absolute path name for the TABLE data base. Consider relocating the GAMESS-UK directory such that this absolute name is less than 45 characters.

Q. Where do I go for help with GAMESS-UK problems?

A. First, look at the FAQ (this page) and our CCPForge site to see if your problem is described. If you cannot find any reference to your problem, please send an e-mail to gamess-uk users email list with a description of your problem, plus the associated output that demonstrates the problem.

Q. Where do I go to find out more about Global Arrays?

A. Take a look at the Global Arrays Support Page. If you wish to pursue your interest, please send an e-mail to Jarek Nieplocha at PNNL.

Diagnosing Common Error Messages

Q. I get the error message:

i/o error; logical file =ed2


i/o error; logical file =ed3

A. These types of errors are caused by GAMESS-UK being unable to find one of the files it creates as it is running. There are a number of reasons why this might happen, but two are most likely.

The first is that you are running two jobs in the same directory at the same time and not specifying the names of the files ed2 and ed3. Each run of gamess will therefore create the files ed2 and ed3 and both runs will be reading and writing to the same files. When they clash you see the io error.

To avoid this (whilst using the gui) you can specify the names of ed2 and ed3 within the File Path group of the GAMESS-UK Job Tab. If you just click on the keep button the file will be renamed with the name of the job, so just make sure that both your jobs have different names. If you are running GAMESS from the command line you will need to set the environment variables ed2 and ed3. If you are using the rungamess script, the -k ed2= command line option should work.

The other (and less likely) reason why this might happen is that you are either running out of diskspace on the directory you are running the job on (so GAMESS can't write to the files), or your filesystem is corrupted and the files aren't behaving as they should be. In either case, this is a problem related to your computer set up.

Q. I am trying to calculate properties for an mp2 wavefunction, using natural orbitals but the code crashes and I see the error message:

mp2 density matrix not found

**** mp2 natural orbitals not generated

A. The problem here is that the default runtype will not calculate the gradient for the mp2 calculation, so you need to do this explicitly by adding the directive:

runtype gradient

To your input file