1% 2% $Id$ 3% 4\label{sec:scfgrad} 5 6 7The input for this directive allows the user to adjust the print control 8for the SCF, UHF, ROHF, MCSCF and MP2 gradients. The 9form of the directive is as follows: 10 11% RJH removed 12% [chkpt <integer minutes>] 13% [restart] 14 15\begin{verbatim} 16 GRADIENTS 17 [print || noprint] ... 18 END 19\end{verbatim} 20 21%The directive contains two keywords, \verb+chkpt+ and \verb+restart+, 22%that are related to the creation of the gradients. The keyword 23%\verb+chkpt+ allows the user to specify a time interval at which the 24%current values for the forces that make up the gradient are saved, for 25%access by a later calculation. The time interval is specified in the 26%integer variable \verb+minutes+, and defines the number of minutes of 27%elapsed wall-clock time since the start of the calculation when the 28%gradient is written to the runtime database. 29%RJH: No default chkpt value? What happens if this is not specified?--fmr. 30 31% \section{CHKPT} 32 33% This keyword is used to specify a time interval after which a 34% checkpoint for later restart is created. After \verb+minutes+ 35% minutes of walltime the forces are written to the runtime database. 36 37% \section{RESTART} 38 39%Specifying the keyword \verb+restart+ allows the user to restart a calculation 40%using the gradient from a previous calculation that may have 41%aborted for some reason (This implies, of course, that the previous 42%calculation employed the keyword \verb+chkpt+ with a value specified for 43%the variable \verb+minutes+, which allowed the calculation to write out the 44%gradient before failing). The keyword \verb+restart+ allows the partially 45%calculated forces from the previous calculation to be used as the starting 46%point for the new calculation. If the gradient was not saved previously, 47%however, this keyword has no effect, and the gradients are automatically 48%recalculated from zero. 49 50% This keyword tells the program that this is a restart of an aborted 51% gradient calculation. The partially calculated forces are taken from 52% the database of the previous run. If they are not present, the 53% keyword is ignored and a complete calculation of the gradients is started. 54 55% This also works within a geometry optimization. Once a gradient 56%calculation has completed, restart information is automatically 57%deleted 58%so that subsequent gradient 59% calculations are not treated as restarts. 60%RJH: I don't get the significance of this paragraph. Elaborate on it? 61%Is it saying that gradient calculations can be saved and restarted even 62%if you are in the middle of a geometry optimization? But once a 63%gradient is completely calculated, the data that got you there is 64%erased, even if you do have a chkpt directive statement?--fmr. 65 66% \section{PRINT, NOPRINT} 67 68The complementary keyword pair \verb+print+ and \verb+noprint+ allows 69the user some additional control on the information that can be 70included in the print output from the SCF calculation. Currently, 71only a few items can be explicitly invoked via print control. These 72are as follows: 73 74% Currently only some print control is available. 75 76\begin{table}[htbp] 77\begin{center} 78\begin{tabular}{lcc} 79 {\bf Name} & {\bf Print Level} & {\bf Description} \\ 80 ``information'' & low & calculation info\\ 81 ``geometry'' & high & geometry information\\ 82 ``basis'' & high & basis set(s) used\\ 83 ``forces'' & low & details of force components\\ 84 ``timing'' & default & timing for each phase\\ 85\end{tabular} 86\end{center} 87\caption{Gradient Print Control Specifications} 88\end{table} 89 90 91