Coulomb Blockade Peak Spacing Fluctuations in Deformable Quantum Dots: A Further Test of Random Matrix Theory

We propose a mechanism to explain the fluctuations of the ground state energy in quantum dots in the Coulomb blockade regime. Employing random matrix theory we show that shape deformations may change the adjacent peak spacing distribution from Wigner-Dyson to nearly Gaussian even in the absence of charging energy fluctuations. The distribution is determined by the average number of anticrossings between successive conductance peaks and the presence or absence of a magnetic field. Our mechanism is tested in a dynamical model whose classical dynamics is chaotic. The results are in good agreement with experiments and apply to spin resolved or spin degenerate states.