Buch, Englisch, Band 3, 212 Seiten, Format (B × H): 170 mm x 244 mm, Gewicht: 402 g
Reihe: Lecture Notes in Chemistry
A Documentation
Buch, Englisch, Band 3, 212 Seiten, Format (B × H): 170 mm x 244 mm, Gewicht: 402 g
Reihe: Lecture Notes in Chemistry
ISBN: 978-3-540-08344-3
Verlag: Springer Berlin Heidelberg
In this chapter ve shall discuss the calculation of potential energy associated vith molecular conforaations. Raving obtained cartesian atoaic coordinates defining conforaations. and lists of intraao- cular interactions, as described in Chapter 3, ve are ready to calculate a quantity which in the chemical literature is known as the total aolecular potential energy or the conforaational, steric, strain or intraaolecular energy. ~he conformational energy of a aolecule can be expressed as a function, of all internal coordinates and interatoaic distances, or as a function of atoaic positions specified by soae general coordi Dates. ~he function, is supposed to haye local ainiaa corresponding to the stable equilibrium conforaations of a aolecule in vacuo, Deglecting interaolecular interactions. ~he exact fora of Y is. of course, unknown. We assume that it can be suitably approximated by a sua of different types of energy contri hutions:, = Y., +, +,., be. nb e ~he teras represent cODtributions to the total aolecular potential energy, due to bond stretching and coapression teras Vb' valence aDgle bending teras 'e' iDterDal rotational or torsional teras V,. DOD-bonded interactions 'nb and electrostatic or Couloab iDter actions 'e. If there are other intraaolecular aechanisas affecting 79 V, sucD as hydrogen bonding, corresponding terms say be added.
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Research
Autoren/Hrsg.
Weitere Infos & Material
Contests.- 1 Introduction.- 1.1 What the CFF is.- 1.2 Background.- 1.3 Pre-CFF.- 1.4 The ascent of CFF.- 1.5 In the wake of CFF.- 2 The Programming System.- 2.1 Introduction.- 2.2 Outline of the programming system.- 2.3 Other programmes.- 2.4 Organisation of the system.- 2.5 Input manual.- 3 Molecular Topology and Geometry.- 3.1 Molecular topology.- 3.2 Lists of interactions.- 3.3 Molecular geometry.- 4 The Conformational Energy and its Derivatives.- 4.1 Introduction.- 4.2 Intermolecular forces.- 4.3 Intramolecular forces.- 4.4 Force field parametrisation.- 4.5 Energy calculations.- 4.6 Numerical calculation of derivatives.- 5 Energy Minimisation.- 5.1 Statement of the problems.- 5.2 Minimisation algorithms.- 5.3 Unified approach to gradient algorithms.- 5.4 Evaluation of minimisation methods.- 5.5 The minimisation programme.- 5.6 Concluding remarks.- 6 Vibrational Calculations.- 6.1 The vibrational problem.- 6.2 Normal coordinates.- 6.3 Programme VIBRAT.- 6.4 Practical considerations.- 7 Optimisation of Energy Parameters.- 7.1 The basic algorithm.- 7.2 The partial derivatives.- 7.3 Implementation of the optimisation.- 8 Developing A Force Field.- 8.1 The concept of energy functions.- 8.2 Examples.- 9 References.
