Larkin and Khmelnitskii’s 1969 paper on one of these phenomena in uniaxial ferroelectrics was an early use of field-theoretic methods in condensed matter physics. For 10 points each:
[10e] Name these phenomena in thermodynamics at which material properties change discontinuously.
ANSWER: phase transitions
[10h] Larkin and Khmelnitskii treated the singularity with a summation of parquet diagrams that have the two-particle form of this property. Diagrams with the one-particle form of this property contribute to the vertex function.
ANSWER: irreducibility [accept one-particle irreducible or 1PI; accept two-particle irreducible or 2PI]
[10m] The heat capacity was found to differ from this eponymous theory’s predictions by a logarithmic factor. This early theory of phase transitions Taylor-expands the free energy in powers of the order parameter.
ANSWER: Landau theory [accept Landau–Ginzburg theory or Ginzburg–Landau theory]
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