Mark Child

Photo of Mark Child

Professor Mark Child FRS

Emeritus Professor



Mark Child was Coulson Professor of Theoretical Chemistry from 1994 to 2004 and is an Emeritus Fellow of St Edmund Hall.

Research Interests

My research concerns the interpretation and prediction of novel dynamical behavior in isolated molecules.

Rydberg Spectroscopy of polyatomic molecules 

Modern VUV and XUV high resolution laser studies of molecular Rydberg states raise new questions for theoretical spectroscopy. Interesting features include (i) breakdown of the Born-Oppenheimer approximation as the electronic energy separation becomes comparable even to rotational energy spacings, (ii) aoutoionization arising from inelastic scattering of the electron from the positive ion core, and (iii) new predissociation mechanisms. The aim is to develop a comprehensive theory of these diverse effects, by combining analytical and numerical scattering techniques. Recent work shows how ab initio methods can be extended to arbitrarily highly excited Rydberg states.

Semiclassical theories of complex intramolecular dynamics

Semiclassical methods aim to relate quantum mechanical observables to the underlying classical mechanics. Specific examples include early work on local mode states of small hydrides and interference effects on predissociation rates.  More recently, similar methods indicate a characteristic pattern in quantum level structure at energies close saddle points on the potential surface– now taken as an example of so-called ‘quantum monodromy'.


Rydberg states

Quantum defect theory for asymmetric tops: application to H2O.  M. S. Child and Ch. Jungen, J. Chem. Phys., 93 (1990) 7756.

Rydberg States of H2O.  M. S. Child, Phil. Trans. Roy. Soc (Lond) A., 355 (1997) 1623.

Ab Initio R-matrix/multi-channel quantum defect theory of nitric oxide. M. Hyama and M. S. Child, J. Phys. B, 35 (2002) 1337.

Quantum Level Structures at a Saddle point

Quantum monodromy in H2O: new insight into the quantum level structures of quasi-linear molecules. M. S. Child, T. Weston and J. Tennyson, Mol. Phys., 96 (1999) 371.

Spectroscopic signatures of bond-breaking internal rotation II: Rotation-vibration level structure and quantum monodromy in HCP. M. P. Jacobson and M. S. Child, J. Chem. Phys. 114 (2001) 262.

Quantum Monodromy and Molecular Spectroscopy. M. S. Child, Adv. Chem. Phys. 136 (2007) 39.

Quantum level structures at a Fermi resonance with angular momentum: classical periodic orbits, catastrophe maps and quantum monodromy. C. D. Cooper and M. S. Child, Phys. Chem. Chem. Phys., 7 (2005) 2731.


  1. M. S. Child, Semiclassical Mechanics with Molecular Applications (Oxford University Press, 1991)
  2. M. S. Child, Molecular Collision Theory (Dover, 1996)
  3. M. S. Child, Theory of Molecular Rydberg States (Cambridge University Press)