Explicit formulae for the electrostatic energy, forces and torques between a pair of molecules of arbitrary symmetry

Price, S.L.; Stone, Anthony J.; Alderton, M.

doi:10.1080/00268978400101721

Cited by 203 publications

(126 citation statements)

References 17 publications

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“…For direct comparison of the results, the spherical tensor atomic moments (Price et al, 1984) in Table 5 are expressed in local frames used in the re®nements ( Table 2). As expected on the basis of bond-topological data (Table 4), there are significant discrepancies between theoretical moments and those derived from the ®tted density.…”

Section: Atomic Electrostatic Momentsmentioning

confidence: 99%

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

2002

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In this study, the feasibility of building a database of theoretical atomic deformation density parameters applicable to the construction of the densities of biomacromolecules and to the interpretation of their X-ray diffraction data is discussed. The procedure described involves generation of valence-only structure factors of tripeptides calculated from theoretical densities at the B3LYP level and the re®nement of multipole parameters against these simulated data. Our results so far indicate that the backbone pseudoatoms extracted in such a way are highly transferable and fairly invariant with respect to rotations around single bonds in the peptide framework. The ultimate goal is to use the aspherical-atom database for improved macromolecular re®nements that are based on high-resolution data and for prediction of electrostatic properties of larger molecules.

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Section: Atomic Electrostatic Momentsmentioning

confidence: 99%

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

2002

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“…(2) The function T λ,λ (R AB , AB ) is the well-known 6 interaction between a multipole Q λ of molecule A and a multipole Q λ of molecule B. It consists of the product of an orientation-dependent function and the inverse power of separation R −l−l −1 AB .…”

Section: Introductionmentioning

confidence: 99%

Time‐dependent coupled‐cluster calculations of polarizabilities and dispersion energy coefficients

Wheatley

2007

J Comput Chem

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Time-dependent coupled cluster theory, with unrestricted electron spins and full treatment of orbital rotation, is used to calculate polarizabilities at imaginary frequencies for Li, Ar, HCl, CO, N 2 , O 2 , and H 2 O, and to obtain dispersion energy coefficients for their pair interactions. Results obtained with augmented quadruple-zeta basis sets agree well with the best literature values of the C 6 dispersion energy coefficients. Time-dependent coupled cluster with single and double excitations theory will be useful as a benchmark for evaluating more approximate theories.

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“…Electrostatic interactions can be problematic in molecular simulation because of the slow decay of the interaction with molecular separation. However, an efficient way to model electrostatic interactions in non-polar molecules is to use a point quadrupole potential 25 , the formula for which is given in equation 18 of Deublein et al 24 . This quadruple potential requires a single parameter per molecular species, the quadrupole moment, Q.…”

Section: Molecular Potentialsmentioning

confidence: 99%

“…Table 2 2CLJQ Force-fields for nitrogen, oxygen, argon and hydrogen from the literature and optimised force-fields from this work. The parameters ε and σ refer to alike molecules, η and ξ specify the interaction parameters between unlike molecules via the mixing rules (eqns (2) and (3)) and Q parameterised the quadrupole interaction between both the like and unalike molecules, via the standard quadrupole formula l 24,25 .…”

Section: Molecular Potentialsmentioning

confidence: 99%

Molecular simulation of the thermophysical properties and phase behaviour of impure CO₂ relevant to CCS

2016

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Impurities from the CCS chain can greatly influence the physical properties of CO 2 . This has important design, safety and cost implications for the compression, transport and storage of CO 2 . There is an urgent need to understand and predict the properties of impure CO 2 to assist with CCS implementation. However, CCS presents demanding modelling requirements. A suitable model must both accurately and robustly predict CO 2 phase behaviour over a wide range of temperature and pressure, and maintain that predictive power for CO 2 mixtures with numerous, mutually interacting chemical species. A promising technique to address this task is molecular simulation. It offers a molecular approach, with foundations in firmly established physical principles, along with the potential to predict the wide range of physical properties required for CCS. The quality of predictions from molecular simulation depends on accurate force-fields to describe the interactions between CO 2 and other molecules. Unfortunately, there is currently no universally applicable method to obtain force-fields suitable for molecular simulation.In this paper we present two methods of obtaining force-fields: the first being semi-empirical and the second using ab initio quantum-chemical calculations. In the first approach we optimise the impurity force-field against measurements of the phase and pressure-volume behaviour of CO 2 binary mixtures with N 2 , O 2 , Ar and H 2 . A gradient-free optimiser allows us to use the simulation itself as the underlying model. This leads to accurate and robust predictions under conditions relevant to CCS. In the second approach we use quantum-chemical calculations to produce ab initio evaluations of the interactions between CO 2 and relevant impurities, taking N 2 as an exemplar. We use a modest number of these calculations to train a machine-learning algorithm, known as a Gaussian process, to describe these data. The resulting model is then able to accurately predict a much broader set of ab initio force-field calculations at comparatively low numerical cost. Although our method is not yet ready to be implemented in a molecular simulation, † Electronic Supplementary Information (ESI) available: [details of any supplementary information available should be included here]. See

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Explicit formulae for the electrostatic energy, forces and torques between a pair of molecules of arbitrary symmetry

Cited by 203 publications

References 17 publications

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

Time‐dependent coupled‐cluster calculations of polarizabilities and dispersion energy coefficients

Molecular simulation of the thermophysical properties and phase behaviour of impure CO₂ relevant to CCS

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Explicit formulae for the electrostatic energy, forces and torques between a pair of molecules of arbitrary symmetry

Cited by 203 publications

References 17 publications

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

Aspherical-atom scattering factors from molecular wave functions. 1. Transferability and conformation dependence of atomic electron densities of peptides within the multipole formalism

Time‐dependent coupled‐cluster calculations of polarizabilities and dispersion energy coefficients

Molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS

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Product

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Molecular simulation of the thermophysical properties and phase behaviour of impure CO₂ relevant to CCS