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| geometry_optimization_optg [2026/03/01 09:25] – [Options for numerical gradients] werner | geometry_optimization_optg [2026/03/01 09:30] (current) – [Options for numerical gradients] werner |
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| * **''FOURPOINT''** (logical). Use 4-point formula for accurate numerical gradient. | * **''FOURPOINT''** (logical). Use 4-point formula for accurate numerical gradient. |
| * **''NUMERICAL''** (logical). Force the use of numerical gradients, even if gradients are available. | * **''NUMERICAL''** (logical). Force the use of numerical gradients, even if gradients are available. |
| * **''MPPX''** (logical). Can be used to disable mppx in the calculation of numerical gradients and hessians (see also ''MPPX_HESS'' below). | * **''MPPX''** (logical). Can be used to disable mppx in the calculation of numerical gradients and hessians (see also ''MPPX_HESS'' below). ''MPPX=1'' (default) means that each geometry displacement is computed on a different processor. |
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| In special cases the energy calculations may require several steps with different occupations and/or symmetries. In this case the ''FORCEINP'' directive must be given (see section [[geometry optimization (OPTG)#miscellaneous options:|miscellaneous options:]]). | In special cases the energy calculations may require several steps with different occupations and/or symmetries. In this case the ''FORCEINP'' directive must be given (see section [[geometry optimization (OPTG)#miscellaneous options:|miscellaneous options:]]). |
| * **''MAXUPD''=//maxupd//** Max number of Hessian updates. The count is reset to zero each time a Hessian is computed. | * **''MAXUPD''=//maxupd//** Max number of Hessian updates. The count is reset to zero each time a Hessian is computed. |
| * **''NUMDIAG''** If true, replace diagonal elements of model hessian by diagonal numerical hessian (if available). This sometimes improves convergence, but since it may lead to symmetry breaking it is no the default. | * **''NUMDIAG''** If true, replace diagonal elements of model hessian by diagonal numerical hessian (if available). This sometimes improves convergence, but since it may lead to symmetry breaking it is no the default. |
| * **''MPPX_HESS''** Can be used to disable or enable mppx in hessian calculations during the optimization. Default is setting of MPPX. | * **''MPPX_HESS''** Can be used to disable or enable mppx in hessian calculations during the optimization. Default is setting of MPPX in section [[[[geometry optimization (OPTG)#Options for numerical gradients|Options for numerical gradients]]]. |
| Note that there are restrictions for computing Hessians for multireference methods (MCSCF, MRCI, ACPF,AQCC,RS2). For these methods the symmetry must not change by any displacements, since this could change the occupations and states and may lead to non-contiguous potential energy surfaces. One of the following three options can be used in these cases: | Note that there are restrictions for computing Hessians for multireference methods (MCSCF, MRCI, ACPF,AQCC,RS2). For these methods the symmetry must not change by any displacements, since this could change the occupations and states and may lead to non-contiguous potential energy surfaces. One of the following three options can be used in these cases: |
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