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.