School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.|School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.|School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.|School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.|School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.|School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, UK.