A reactive force field simulation of liquid-liquid phase transitions in phosphorus

A force field model of phosphorus has been developed based on density functional (DF) computations and experimental results, covering low energy forms of local tetrahedral symmetry and more compact (simple cubic) structures that arise with increasing pressure. Rules tailored to DF data for the addition, deletion, and exchange of covalent bonds allow the system to adapt the bonding configuration to the thermodynamic state. Monte Carlo simulations in the N-P-T ensemble show that the molecular (P-4) liquid phase, stable at low pressure P and relatively low temperature T, transforms to a polymeric (gel) state on increasing either P or T. These phase changes are observed in recent experiments at similar thermodynamic conditions, as shown by the close agreement of computed and measured structure factors in the molecular and polymer phases. The polymeric phase obtained by increasing pressure has a dominant simple cubic character, while the polymer obtained by raising T at moderate pressure is tetrahedral. Comparison with DF results suggests that the latter is a semiconductor, while the cubic form is metallic. The simulations show that the T-induced polymerization is due to the entropy of the configuration of covalent bonds, as in the polymerization transition in sulfur. The transition observed with increasing P is the continuation at high T of the black P to arsenic (A17) structure observed in the solid state, and also corresponds to a semiconductor to metal transition. (C) 2004 American Institute of Physics.

The African National Congress and its Critics: 'Predatory Liberalism', Black Empowerment and Intra-Alliance Tensions in Post-Apartheid South Africa

Post-apartheid South Africa is characterized by centralized, neo-liberal policymaking that perpetuates, and in some cases exaggerates, socio-economic inequalities inherited from the apartheid era. The African National Congress (ANC) leadership’s alignment with powerful international and domestic market actors produces tensions within the Tripartite Alliance and between government and civil society. Consequently, several characteristics of ‘predatory liberalism’ are evident in contemporary South Africa: neo-liberal restructuring of the economy is combined with an increasing willingness by government to assert its authority, to marginalize and delegitimize those critical of its abandonment of inclusive governance. A new form of oligarch power, combining entrenched economic interests with those of a new ‘black bourgeoisie’ promoted by narrowly implemented Black Economic Empowerment policies, diminishes prospects for broad-based socio-economic transformation. Because the new policy environment is failing to resolve tensions between global market demands for increasing market liberalization and domestic popular demands for poverty-alleviation and socio-economic transformation, the ANC leadership is forced increasingly to confront ‘ultra-leftists’ who are challenging its credentials as defender of the National Democratic Revolution which was the cornerstone in the anti-apartheid struggle.

The New Face of Global Hollywood: Black Hawk Down and the Politics of Meta-Sovereignty

This paper uses Ridley Scott’s 2001 film blockbuster Black Hawk Down to examine the claim that popular film is the ‘newest component of sovereignty’. While the topic of the film – the 1993 UN/US intervention in Somalia – lends itself to straightforward politicisation, this paper is equally interested in the film’s production history and its reception by global audiences. While initial reactions to the film focused on its ideological commitments (e.g. racism, collusion between Hollywood and the Pentagon, post-11 September patriotism), these readings continually posed an imagined ‘America’ against ‘the world’. This paper argues that Black Hawk Down is not about sovereignty as traditionally conceived, that is, about national interest shaping global affairs. Rather, Black Hawk Down articulates, and is articulated by, a new and emerging global order that operates through inclusion, management and flexibility. Drawing on recent theoretical debates over this new logic of rule, this paper illustrates how Black Hawk Down invoked much more diffuse, complex and deterritorialized categories than national sovereignty. In effect, Scott’s film goes beyond traditional notions of sovereignty altogether: its production, signification and reception deconstruct simple notions of ‘America’ and ‘the world’ in favour of what Hardt and Negri call ‘Empire’, what Zizek calls ‘post-politics’, and what we refer to as ‘meta-sovereignty’.