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| 3. Since RESP only support nonrelativistic calculations currently, spin-free X2C based approach can not be used in optimization [to be changed in future]. |
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| Algorithm for optimization, default L-BFGS | {{{ 3: search for minima using RFO step 10: search for saddle points using P-RFO step }}} Default: 3 === UPDATE === Algorithm for Hessian update. {{{ 0: calculate numerical Hessian at every step 1: Powell update for saddle points (solver=0 only) 2: Bofill update for saddle points 3: L-BFGS update (solver=0) or BFGS update (solver=1) 9: Bofill update for minima }}} If update is not 0, a molecular mechanics Hessian will be built at the first step of the geometry optimization. Default: 3 |
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| Coordinates | {{{ 0: Cartesian coordinates (ignored if solver=1, since the BDF solver can only use redundant internal coordinates) 1: Redundant internal coordinates }}} |
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=== CONSTRAIN === Invokes constrained optimization.<<BR>> The first line after the keyword is the number of constraints, N. The 2nd to (N+1)th lines each consists of 2 to 4 integers, which are to be interpreted as atomic serial numbers.<<BR>> If 2 integers are given, then the bond between the two atoms is frozen.<<BR>> If 3 integers are given, then the angle between the three atoms is frozen.<<BR>> If 4 integers are given, then the dihedral between the four atoms is frozen.<<BR>> === HESS === Calculates numerical Hessian. The following line must be one of the following four keywords: {{{ only calculates the numerical Hessian without performing a geometry optimization. This also gives the vibrational frequencies, vibrational modes, and thermochemical functions such as ZPE, inner energy, enthalpy, entropy and Gibbs free energy. init calculates the numerical Hessian, then performs geometry optimization using the Hessian as the initial Hessian. This is useful for transition state optimizations, where the default molecular mechanics Hessian is of poor quality. The vibrational frequency and thermochemistry analyses are not performed. final does geometry optimization, and if the geometry optimization converges, calculates the numerical Hessian at the converged structure. The vibrational frequency and thermochemistry analyses are performed. init+final calculates the Hessian both before and after geometry optimization. The vibrational frequency and thermochemistry analyses are performed on the final Hessian, but not on the initial Hessian. }}} To save computational costs, Hessians whose only role is to aid geometry convergence are calculated using single-sided finite difference. Otherwise, two-sided finite difference is used, which provides better accuracy. === RECALCHESS === The next line must be an integer, x. The numerical Hessian is recalculated every x geometry optimization steps. === NUMHESSSTEP === Step length used in the finite-difference numerical Hessian procedure (unit: Bohr). Default: 0.001. |
bdfopt
Contents
Introduction
Geometry optimiser of BDF package. This BDFOPT module can be used to find minimal points, saddle points and also conical intersection points. For details of the interface, see bdfopt/, module/bdfopt_mod.F90,dlfind_module.F90, sys_util/bdf_dlfind_util.F90 for interface.
Two optimizers can be used by specifying the solver keyword:
1. [solver=1] Original optimizer in BDF developed by Dr. Yong Zhang using redundant internal coordinates (more efficient!).
2. [solver=0] Interface to the package - DL-FIND. For details, see: http://ccpforge.cse.rl.ac.uk/gf/project/dl-find/
"DL-FIND: An Open-Source Geometry Optimizer for Atomistic Simulations", Johannes Kästner, Joanne M. Carr, Thomas W. Keal, Walter Thiel, Adrian Wander and Paul Sherwood, J. Phys. Chem. A, 2009, 113 (43), 11856-11865. DOI: 10.1021/jp9028968
The optimization information is stored in filename.pes1 [ground state/excited state] or filename.pes2 [conical intersection].
Currently, the following methods are available:
1. HF/MCSCF with GRAD module
2. HF/DFT/TD-DFT with RESP modules
This preliminary version has several limitations:
1. Change of symmetry during optimization is not correctly handled for excited state optimization, because the correct input file needs to be prepared.
2. Conical intersection optimization does not work properly!
Examples
General keywords
IPRT
Print level.
SOLVER
=0, DLFIND; =1, BDF optimizer
MAXCYCLE
TOLGRAD
TOLENE
IOPT
3: search for minima using RFO step 10: search for saddle points using P-RFO step
Default: 3
UPDATE
Algorithm for Hessian update.
0: calculate numerical Hessian at every step 1: Powell update for saddle points (solver=0 only) 2: Bofill update for saddle points 3: L-BFGS update (solver=0) or BFGS update (solver=1) 9: Bofill update for minima
If update is not 0, a molecular mechanics Hessian will be built at the first step of the geometry optimization. Default: 3
ICOORD
0: Cartesian coordinates (ignored if solver=1, since the BDF solver can only use redundant internal coordinates) 1: Redundant internal coordinates
IMULTI
multi-state optimization for conical intersection
ILINE
line search
CONSTRAIN
Invokes constrained optimization.
The first line after the keyword is the number of constraints, N. The 2nd to (N+1)th lines each consists of 2 to 4 integers, which are to be interpreted as atomic serial numbers.
If 2 integers are given, then the bond between the two atoms is frozen.
If 3 integers are given, then the angle between the three atoms is frozen.
If 4 integers are given, then the dihedral between the four atoms is frozen.
HESS
Calculates numerical Hessian. The following line must be one of the following four keywords:
only calculates the numerical Hessian without performing a geometry optimization. This also gives the vibrational frequencies, vibrational modes, and thermochemical functions such as ZPE, inner energy, enthalpy, entropy and Gibbs free energy. init calculates the numerical Hessian, then performs geometry optimization using the Hessian as the initial Hessian. This is useful for transition state optimizations, where the default molecular mechanics Hessian is of poor quality. The vibrational frequency and thermochemistry analyses are not performed. final does geometry optimization, and if the geometry optimization converges, calculates the numerical Hessian at the converged structure. The vibrational frequency and thermochemistry analyses are performed. init+final calculates the Hessian both before and after geometry optimization. The vibrational frequency and thermochemistry analyses are performed on the final Hessian, but not on the initial Hessian.
To save computational costs, Hessians whose only role is to aid geometry convergence are calculated using single-sided finite difference. Otherwise, two-sided finite difference is used, which provides better accuracy.
RECALCHESS
The next line must be an integer, x. The numerical Hessian is recalculated every x geometry optimization steps.
NUMHESSSTEP
Step length used in the finite-difference numerical Hessian procedure (unit: Bohr). Default: 0.001.