The inclusion of electron correlation in intermolecular potentials: applications to the formamide dimer and liquid formamide

Abstract

A test of the quality of the electrostatic properties and polarizabilities used in the nonempirical molecular orbital (NEMO) potential is carried out for formamide by calculating the molecular dipole moment and polarizability at the second-order Mùller±Plesset (MP2) level of theory. The molecular dipole moment is 11% lower at the MP2 level than at the Hartree±Fock (HF) level, whereas the isotropic part of the polarizability is increased by 36% by adding electron correlation and using a considerably larger basis set. The atomic charges, dipole moments and polarizabilities obtained at the HF level are rescaled to get the correct molecular properties at the MP2 level. The potential minimum for the cyclic dimer of formamide is À17:50 kcal/mol with the MP2-scaled properties and is signi®cantly lower than other potentials give. Two intermolecular potentials are constructed and used in subsequent molecular dynamics simulations: one with the regular NEMO potential and the other with the rescaled MP2 properties. A damping of the electrostatic ®eld at short intermolecular distances is included in the present NEMO model. The average energies for liquid formamide are lower for the MP2-scaled model and are in good agreement with experimental results. The lowering of the simulation energy for the MP2-scaled potential indicates the strong dispersive interactions in liquid formamide.

Biomolecular electrostatics and solvation: a computational perspective

“…Inclusion of polarization allows more rigorous parameterization and validation of the force field against a wide range of molecular systems in different environment, from small molecules to macromolecules, from gas-phase to condensed-phase properties. The advantages of polarizable force fields have been demonstrated for water (Lamoureux et al, 2003; Ren & Ponder, 2003; Stern et al, 2001), amides and other organic molecules (Brdarski et al, 2000; Hagberg et al, 2005; Harder et al, 2008; Lopes et al, 2007; Ren et al, 2011; Wang et al, 2011a; Wang et al, 2011b), ions (Grossfield et al, 2003; Jiao et al, 2008; Patel et al, 2009; Wu et al, 2010; Yu et al, 2010), membranes (Bauer et al, 2011), and ligand-protein complexes (Jiao et al, 2008; Roux et al, 2011). Of equal importance is the development of efficient particle-mesh.…”

Polarizable Atomic Multipole-Based Molecular Mechanics for Organic Molecules

“…41,42 The modeling of neat organic liquids, including alcohols, acids, amides and aromatics, has also been reported using polarizable potentials. 11,22,35,43–50 …”

Molecular dynamics study of response of liquid N,N-dimethylformamide to externally applied electric field using a polarizable force field

“…26 A multicentre multipole expansion (MME) charge distribution over the atoms in molecules and polarizabilities were used in the nonempirical molecular orbital (NEMO) potential and tested with liquid formamide, where the molecular dipole moment and polarizabilities are scaled using rations of the values obtained from the second-order Møller-Plesset (MP2) and the SCF calculations. 39 A polarizable intermolecular potential function (PIPF) for the simulation of liquid amides was developed by introducing a nonadditive polarization term and the empirical parameters were optimized through Monte Carlo simulations of liquid formamide, N-methylacetamide, N-methylformamide, and N,N-dimethylformamide. 40 The induced dipole model (PIPF) was introduced into CHARMMA and its applications to liquid amides, including formamide, N-methylacetamide, and N-methylformamide, and N,N-dimethylformamide was discussed.…”