There are several conditions when the static program will give nonsensical results. These occur when something in the crystal structure takes us outside the range of validity of the Slater-Koster parameters in the Tight-Binding Parameters Database. Two cases typically occur:

• In the first case, the overlap matrix of the Slater-Koster parametrization becomes unphysical, i.e., it develops a negative eigenvalue. This indicates that no actual set of wave-functions could produce this particular matrix. Typically this will occur when two or more atoms get close together. We are working on parametrization forms for the overlap matrix elements which will avoid this difficulty.
• In the second case, we exceed the range of the parametrization fitting and the energy behaves badly. Typically we see the total energy begin to decrease as we go to small volumes, even when the overlap matrix remains physical (positive definite).

If these situations occur, please contact the authors to determine if a better set of tight-binding parameters has been or can be developed.

If other errors occur, please examine your SKIN input file very carefully, using the Examples in the Usage section as a guide. Information printed via the TWEAKS mechanism should help. It may also be useful to uncomment some of the output lines in the code itself, recompile, and run the code again, noting the new informational output. These lines are commented with c$$$ beginning in column 1. Generally these lines were used as we debugged the code, so uncommenting some of them to determine the program flow is a good place to start.

To report bugs in static, please send email to D.A. Papaconstantopoulos (dpapacon@gmu.edu). Describe the conditions that you found the bug. A (brief) sample input and output which replicates the bug will be very useful.

Finally, this manual has been checked, rechecked, and cross-checked. Therefore I am sure that there are no more than 5-10 errors per page. I'll grudgingly acknowledge and correct errors in spelling or grammar. Reports of errors caused by invalid links will be treated kindly. Pointers to things left unclear will be attended to promptly. Reports of errors in equations will be received graciously, especially if you include the fix. Please send any of the above to dpapacon@gmu.edu.

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Current URL: http://esd.cos.gmu.edu/tb/static/trouble_shoot.html