Computational Chemistry - Semiempirical Methods

RM1: a Reparameterization of AM1 for H, C, N, O, P, S, F, Cl, Br, and I

Gerd Bruno Rocha, Ricardo Oliveira Freire, Alfredo Mayall Simas*, and James J. P. Stewart.
Journal of Computational Chemistry 27(10), 1101-1111, 2006

lanthanides rm1

GPU linear algebra libraries and GPGPU programming for accelerating MOPAC semiempirical quantum chemistry calculations

Authors: Julio Daniel Carvalho Maia, Gabriel Aires Urquiza Carvalho, Carlos Peixoto Mangueira, Sidney Ramos Santana, Lucídio Anjos Formiga Cabral, and Gerd Bruno Rocha
Publication year: 2012
Journal / Book title:  Journal of Chemical Theory and Computation

Advanced Corrections of Hydrogen Bonding and Dispersion for Semiempirical Quantum Mechanical Methods

Authors: Jan Řezáč and Pavel Hobza
Publication year: 2011
Journal / Book title: J. Chem. Theory Comput.

Optimal Scaling Factors for CM1 and CM3 Atomic Charges in RM1-Based Aqueous Simulations

Authors: Jonah Z. Vilseck, Somisetti V. Sambasivarao, and Orlando Acevedo
Publication year: 2011
Journal / Book title: Journal of Computational Chemistry

Conformational Analysis of Toxogonine, TMB-4 and HI-6 using PM6 and RM1 Methods

Authors: Arlan da Silva Gonçalves, Tanos C. C. França, José D. Figueroa-Villar and Pedro G. Pascutti
Publication year: 2010

Extension of the MST continuum solvation model to the RM1 semiempirical Hamiltonian

Author(s): Flavio Forti, Xavier Barril, F. Javier Luque, and Modesto Orozco
Publication year: 2008

Harmonic vibrational frequency scaling factors for the new NDDO Hamiltonians: RM1 and PM6

Author(s): Z. A. Fekete, E. A. Hoffmannz, T. Kortvelyesi, and B. Penke
Publication year: 2007
Journal / Book title: MOLECULAR PHYSICS


  • RM1 is a fully disclosed, and public domain semiempirical molecular orbital model.

  • Capable of modeling most molecular systems of importance to organic chemistry, biochemistry and pharmaceutical research;

  • Essentially identical to the AM1 method, but with improved performance - with much newer and better parameters.

  • A known error in PM3 nitrogen charges is corrected in RM1.

  • In most cases, RM1 yields superior results to both AM1 and PM3 - for organic and biomolecules.

  • RM1 is different from PM5 and PM6, which use dissimilar equations, mainly affecting the way the core-core interaction is defined.
  • RM1 is one of the most widely available semiempirical methods.


RM1 (Recife Model 1) was named in recognition of the city of Recife, where the model was developed.