and J.L. Yarger. Infrared spectroscopy of germanium diox- ide (GeO 2 ) glass at high pressure. Phys. Chem. Glasses , 46(4):345–349, 2005. 

5 P.S. Salmon, A.C. Barnes, R.A. Martin, and G.J. Cuello. Glass fragility and atomic ordering on the intermediate and extended range. Phys. Rev. Lett. , 96(23):235502, 2006. 6 

P.S. Salmon, A.C. Barnes, R.A. Martin, and G.J. Cuello. Structure of glassy GeO 2 . J. Phys.:Condens. Matter , 19(41):415110, 2007. 7 

M. Micoulaut, Y. Guissani, and B. Guillot. Simulated structure and thermal properties of glassy and liquid ger- mania. Phys. Rev. E , 73(031504), 2006. 8 

J. Peralta, G. Guti´ errez, and J. Rogan. Structural and vibrational properties of amorphous GeO 2 : a molecular dynamics study. J. Phys.:Condens. Matter , 20(14):145215, 2008. 9 

R.D. Oeffner and S.R. Elliott. Interatomic potential for germanium dioxide empirically fitted to an ab initio energy surface. Phys. Rev. B , 58(22):14791–14803, 1998. 10 

L. Giacomazzi, P. Umari, and A. Pasquarello. Medium- range structural properties of vitreous germania obtained through first-principles analysis of vibrational spectra. Phys. Rev. Lett. , 95(7):075505, 2005. 11 

L. Giacomazzi, P. Umari, and A. Pasquarello. Vibrational spectra of vitreous germania from first-principles. Phys. Rev. B , 74(15):155208, 2006. 12 

M. Hawlitzky, J. Horbach, S. Ispas, M. Krack, and K. Binder. Comparative classical and ab initio molecular dynamics study of molten and glassy germanium dioxide. J. Phys.:Condens. Matter , 20(28):285106, 2008. 13 

P.A. Madden, R. Heaton, A. Aguado, and S. Jahn. From first-principles to material properties. J. Mol. Struct.:THEOCHEM , 771:9–18, 2006. 14 

S. Jahn and P.A. Madden. Modeling Earth materials from crustal to lower mantle conditions: a transferable set of interaction potentials for the CMAS system. Phys. Earth Planet. Inter. , 162:129–139, 2007. 15 

M.J. Castiglione, M. Wilson, and P.A. Madden. Polar- ization effects in the simulation of lead (II) fluoride. J. Phys.:Condens. Matter , 11:9009–9024, 1999. 16 

M.J. Castiglione and P.A. Madden. Fluoride ion disor- der and clustering in superionic pbf 2 . J. Phys.: Condens. Matter , 13(44):9963, 2001. 17 

P. Tangney and S. Scandolo. An ab initio parametrized interatomic force field for silica. J. Chem. Phys. , 117(19): 8898-8904, 2002. 18 

The CPMD consortium. CPMD Version 3.x, http://www.cpmd.org. MPI F¨ ur Festk¨ orperforschung 

and the IBM Zurich Research Laboratory. 

19 A. Aguado, L. Bernasconi, S. Jahn, and P.A. Madden. Multipoles and interaction potentials in ionic materials from planewave-dft calculations. J. Chem. Soc., Faraday Discuss. , 124:171–184, 2003. 20 

M. Salanne, R. Vuilleumier, P.A. Madden, C. Simon, P. Turq, and B. Guillot. Polarizabilities of individual molecules and ions in liquids from first principles. J. Phys.:Condens. Matter , 20(49):494207, 2008. 21 

S.T. Norberg, I. Ahmed, S. Hull, D. Marrocchelli, and P.A. Madden. J. Phys.:Condens. Matter , to be submitted. 22 

M. Wilson, S. Jahn, and P.A. Madden. The construc- tion and application of a fully flexible computer simula- tion model for lithium oxide. J. Phys.:Condens. Matter , 16(27):S2795–S2810, 2004. 23 

S. Nos´ e. A molecular dynamics method for simulations in the canonical ensemble. Mol. Phys. , 52:255–268, 1984. 24 

G.J. Martyna, M.L. Klein, and M. Tuckerman. Nos´ e- hoover chains: the canonical ensemble via continuous dy- namics. J. Chem. Phys. , 97(4):2635–2643, 1992. 25 

T. Tokuda and W.D. Kingery. Oxygen diffusion and va- porization rates for liquid and solid germanium dioxide. J. Appl. Phys. , 34:2104–2105, 1963. 26 

M. Wilson, P.A. Madden, M. Hemmati, and C.A. An- gell. Polarization effects, network dynamics, and the in- frared spectrum of amorphous sio 2 . Phys. Rev. Lett. , 77(19):4023–4026, 1996. 27 

J.M. Caillol, D. Levesque, and J.J. Weis. Electrical prop- erties of polarizable ionic solutions. I. Theoretical aspects. J. Chem. Phys. , 91(9):5544–5554, 1989. 28 

J.M. Caillol, D. Levesque, and J.J. Weis. Electrical proper- ties of polarizable ionic solutions. II. Computer simulation results. J. Chem. Phys. , 91(9):5555–5566, 1989. 29 

R.J. Heaton, R. Brookes, P.A. Madden, M. Salanne, C. Si- mon, and P. Turq. A first-principles description of liquid BeF 2 and its mixtures with LiF: 1. potential development and pure BeF 2 . J. Phys. Chem. B , 110(23):11454–11460, 2006. 30 

E.A. Pavlatou, P.A. Madden, and M. Wilson. The inter- pretation of vibrational spectra of ionic melts. J. Chem. Phys. , 107(24):10446–10457, 1997. 31 

K. Trachenko and M.T. Dove. Floppy modes in silica glass under pressure. J. Phys.:Condens. Matter , 14:1143–1152, 2002 . 32 

S. Jahn and P.A. Madden. Structure and dynamics in liq- uid alumina: simulations with an ab initio interaction po- tential. J. Non-Cryst. Solids , 353(32–40):3500–3504, 2007. 

