![]() ![]() If, however, the cosine becomes positive, then the assumption is made that one moiety has fallen over the TS and is now below the other geometry. For as long as it is negative, then the two geometries are on opposite sides of the TS. This situation is verified at every point by calculating the cosine of the angle between the two gradient vectors. During a SADDLEĬalculation the two geometries involved are on opposite sides of the transition state Ī non-fatal message, but still cause for concern. The SADDLE technique uses two geometries, one for the reactant(s) and one for the product(s). ![]() No advice is available for getting round this error. The program has searched in all 3 N-6 directions, and found no way down, but the criteria for a minimum have not been satisfied. Apparently a minimum has been found, but not recognized as such. Bartel's method attempts to minimize the gradient norm by searching the gradient space for a minimum. Ī quite rare message, produced by Bartel's gradient norm minimization. More often, however, this message indicates a mistake, and the calculation is, by default, stopped. This can be done by using the keyword GEO-OK. This can occur when a complicated geometry is being optimized, in which case the user may wish to continue. Two genuine atoms (not dummies) are separated by a very small distance. ATOMS nn AND nn ARE SEPARATED BY nn.nnnn ANGSTROMS (FATAL) This is normally caused by forgetting to specify an atomic number or symbol. ATOMIC NUMBER OF nn ? (FATAL)Īn atom has been specified with a negative or zero atomic number. Typographic error has been made can this be rectified. (FATAL)Īn element has been used for which parameters are not available. H1.008 or +12.00 (for a "+" sparkle having a mass of 12.00.) ATOMIC NUMBER nn IS NOT AVAILABLE. Atom masses are specified as numbers after the symbol, e.g. Sparkles are used, these have no default mass. In a DRC calculation, all atoms must have masses greater than 0.1 times the mass of a hydrogen atom. ![]() If any of these rules is broken, a fatal error message is printed, and the calculation stopped. If the dihedral was with atom 5, then the geometry definition would be faulty. Thus atom 9 might be connected to atom 5, make an angle with atom 6, and have a dihedral with atom 7. If internal, they must be defined in terms of already-defined atoms: these atoms must all be different. All other atoms can be Cartesian or internal. If internal, it must be defined with connectivity (2,1,0) or (1,2,0). If internal, it must be defined with connectivity (1,0,0). The rules for definition of atom connectivity are: 1. Symmetry function 18 (the " z" coordinate is set equal to minus the reference " y" coordinate) using an atom whose position is defined using internal coordinates. (FATAL)Īn attempt has been made to use symmetry function 19 (the bond length is a multiple of the reference bond length) using an atom whose position is defined using Cartesian coordinates. If CPU time is not important, add BAR=0.02 to the original data set and re-run. If it is not near to the transition state, identify geometries on both sides of the transition state (these will be separated in the output by the message "REACTANTS AND PRODUCTS SWAPPED AROUND"), and use these to start a new SADDLE calculation. less than 0.2), refine the geometry using TS. Options at this point are: If it is near to the transition state (the gradient norm has been dropping for reactants or products, or the "DISTANCE A-B" is small, e.g. In a SADDLE calculation, both reactants and products are on the same side of the transition state. In a FORCE calculation, the mass of an atom is zero. AT LEAST ONE ATOM HAS A ZERO MASS (FATAL) This sometimes happens naturally, particularly with exotic systems. This is often caused by faulty data, so the data should be checked to see if anything is wrong. The default SCF convergers have not worked. Check the dependent atom numbers in the symmetry data. A SYMMETRY FUNCTION IS USED TO DEFINE A NON-EXISTENT ATOM (FATAL) S ymmetry functions can only be used in the definition of atoms or dummy atoms. The smallest system that can have vibrations is a diatomic molecule. A SINGLE ATOM HAS NO VIBRATIONAL MODES (FATAL)Īn attempt has been made to calculate the vibrations of a single atom. The pair of options, 1SCF with a path calculation, is not allowed, except in a RESTART calculation. The following alphabetical list gives more complete definitions of the messages printed. However, when an error occurs it is useful to have more information than is given in the standard messages. MOPAC produces several hundred messages, all of which are intended to be self-explanatory. Error messages produced by MOPAC Error messages produced by MOPAC ![]()
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