ENERGY MINIMIZATION
CHEMICAL PROPERTIES
PHYSICAL PROPERTIES
- MM suitable for first and second derivatives
- MM calculate on large system
- Newton-Raphson (small structure)
- SD/NR (mixed method)
Related to stationary point
USES
- To connect transition state with its two closest minima
- More steps taken thus high computational cost
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ab initio
Calculate molecular energies, ionization potentials, electron affinities, and molecular orbitals.
For studying reaction mechanisms, electronic structures, and spectroscopic properties
Determine bond lengths, bond angles, and dihedral angles
METHOD
molecular mechanics
Second Order
Others
First Order
- Steepest descent
- Conjugate gradient
not well-suited for accurately predicting chemical properties.
can estimate bond lengths and angles, but the accuracy is limited.
- Newton-Raphson
- Block-Diagonal Newton-Raphson
- Quasi-Newton-Raphson
- Fletcher-Powell Algorithm
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- Line search
- Simplex
Energy minimization can stop due to stationary point found or the program ran out of steps
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ab initio
If ran out of steps need to do another energy minimization (geometry that has lowest energy)
calculate polarizabilities, dipole moments, and hyperpolarizabilities
provide insights into magnetic properties, such as magnetic moments and magnetic susceptibilities
suitable for studying optical properties, such as absorption and emission spectra.
semi - empirical
predict molecular polarizabilities and some optical properties.
offer insights into the behavior of large molecular systems in the presence of external fields.
molecular mechanics
not well-suited for predicting physical properties accurately.
focus on structural properties rather than electronic or optical properties
provide information on molecular volume, surface area, and flexibility.
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semi-empirical
Suitable for studying larger systems, such as biomolecules
Predict molecular geometries, molecular energies, and some electronic properties.