N Kumar
Articles written in Proceedings – Section A
Volume 73 Issue 6 June 1971 pp 313-323
A theory of the insulator-metal transition in transition-metal compounds is developed in terms of the collapse of the effective energy gap which is a function of the thermally excited electron-hole pairs. This dependence is shown to arise from the hole-lattice interaction. The reaction of the lattice is found to be equivalent to generating an internal positive pressure (strain). Estimates show that the observed typical behaviour of the conductivity jump and the change of volume at the transition temperature can be explained by the present theory.
Volume 74 Issue 2 August 1971 pp 79-82
Quantum kinematics of Fermi-Dirac vacuum-
Following Weisskopf, the kinematics of quantum mechanics is shown to lead to a modified charge distribution for a test electron embedded in the Fermi-Dirac vacuum with interesting consequences.
Volume 74 Issue 2 August 1971 pp 91-98
Quantum theoretic explanation of the Schwarz-Hora effect
Following the path-integral approach we show that the Schwarz-Hora effect is a one-electron quantum-mechanical phenomenon in that the de Broglie wave associated with a single electron is modulated by the oscillating electric field. The treatment brings out the crucial role played by the crystal in providing a discontinuity in the longitudinal component of the electric field. The expression derived for the resulting current density shows the appropriate oscillatory behaviour in time and distance. The possibility of there being a temporal counterpart of Aharonov-Bohm effect is briefly discussed in this context.
Volume 75 Issue 2 February 1972 pp 57-67
On mass quantisation of elementary particles
A semi-phenomenological theory of mass quantisation is presented, wherein different elementary particles are regarded as excited positiveenergy states of a fundamental extensible object. The latter is essentially an elastic continuum which in its quiescent (classical equilibrium) state is believed to be massless and stressless. The classical Hamiltonian describing its oscillations about the equilibrium configuration is constructed by treating the mass-equivalent of the elastic potential energy as the inertial mass occurring in the denominator of the kinetic energy term. Quantisation of the resulting variable-mass oscillator is then effected by following the procedure given by Pauli and Podolsky.
The energy-mass eigenvalues (
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