SIBFA force field

Finally, the charge transfer term is evaluated using the semiem-pirical formalism implemented in the SIBFA force field (Gresh et al., 1979 Piquemal etal., 2007) ... 

Ligand Field Ejfects In order to extend the range of application of the SIBFA force field to metals with partially filled d-shells such as Cu(II) with clear biological importance, a LFSE based on the same AOM introduced in the LFMM approach was recently added [38]. The total interaction energy of a metal-Ugand complex (including a dispersion term F isp for improved agreement with correlated ab initio methods) [46] in SIBFA-LF is defined, therefore, as... 

DEVELOPMENT OF NEXT GENERATION POLARIZABLE FORCE FIELDS FROM SIBFA TO GEM... 

The GEM force field follows exactly the SIBFA energy scheme. However, once computed, the auxiliary coefficients can be directly used to compute integrals. That way, the evaluation of the electrostatic interaction can virtually be exact for an perfect fit of the density as the three terms of the coulomb energy, namely the nucleus-nucleus repulsion, electron-nucleus attraction and electron-electron repulsion, through the use of p [2, 14-16, 58],... 

As electric fields and potential of molecules can be generated upon distributed p, the second order energies schemes of the SIBFA approach can be directly fueled by the density fitted coefficients. To conclude, an important asset of the GEM approach is the possibility of generating a general framework to perform Periodic Boundary Conditions (PBC) simulations. Indeed, such process can be used for second generation APMM such as SIBFA since PBC methodology has been shown to be a key issue in polarizable molecular dynamics with the efficient PBC implementation [60] of the multipole based AMOEBA force field [61]. 

On the basis of a sound analysis of intermolecular interactions, performed by means of a quantum perturbational approach, Claverie derived a force field that could suitably represent intermolecular interactions. The electrostatic interactions are described by means of a distributed multipole analysis, and induction effects are taken into account. The force field sum of interactions between fragments completed ab initio (SIBFA) originated from this study and was subsequently applied successfully to many biophysical problems. 

Accurate energy-decomposition schemes Other force fields build on both atomic multipoles and polarizability to provide an accurate decomposition of intermolecular energies. The sum of interaction between fragments ab initio (sibfa) [83, 84] decomposes the... 

In this contribution, we present the theory behind the GEM method and recent advances and results on the application of two hybrid GEM potentials. In Section 8.2, we provide a brief review of the analytical and numerical density fitting methods and its implementation, including the methods employed to control numerical instabilities. This is followed by a review of the procedure to obtain distributed site multipoles from the fitted Hermite coefficients in Section 8.3. Section 8.4 describes the extension of reciprocal space methods for continuous densities. Section 8.5 describes the complete form for GEM and a novel hybrid force field, GEM, which combines term from GEM and AMOEBA for MD simulations. Finally, Section 8.6 describes the implementation and initial applications of a multi-scale program that combines GEM and SIBFA. 

In our initial implementations of GEM-0 and GEM we have not introduced an explicit term for the dispersion interactions. This is because these force fields have been originally parametrized using the CSOV method at the DFT level, which, by definition, does not include a dispersion contribution. However, it is possible to include this term in a similar way to the SIBFA potential (Gresh et al., 1979 Piquemal et al., 2007). 

The final relative energy e of each of the i d-orbitals is then obtained from the Hamiltonian matrix by diagonalizatimi. Note that only bonds to ligand orbitals with <7 symmetry are presently included in SIBFA-LF an extension to u symmetry analogous to that of the LFMM force field described earlier remains to be implemented. Flfse of a r/" system is calculated from the orbital energies e according to... 

The SIBFA (sum of interactions between fragments ab initio computed) force field for small molecules and flexible proteins, developed by Gresh, Piquemal et al. is one of the most sophisticated polarizable force fields because it incorporates polarization, electrostatic penetration, " and charge transfer effects. ... 

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