96 citations · 214 across the 15 of their papers we have counts for
10 papers · 1 filter
Quantum Breathers in a Nonlinear Lattice
W. Z. Wang, J. Tinka Gammel, A. R. Bishop +1
We study nonlinear phonon excitations in a one-dimensional quantum nonlinear lattice model using numerical exact diagonalization. We find that multi-phonon bound states exist as ei…
Pressure Tuning of the Charge Density Wave in the Halogen-Bridged Transition-Metal (MX) Solid
G. S. Kanner, J. Tinka Gammel, S. P. Love +3
We report the pressure dependence up to 95 kbar of Raman active stretching modes in the quasi-one-dimensional MX chain solid . The data indicate that a predicted…
Improved Mean-Field Scheme for the Hubbard Model
J. C. Hicks, J. Tinka Gammel
Ground state energies and on-site density-density correlations are calculated for the 1-D Hubbard model using a linear combination of the Hubbard projection operators. The mean-fie…
Comment on Tuning of the CDW in MX Chains
J. Tinka Gammel
In M. Alouani et al., Phys. Rev. Lett. 71, 1415 (1993), the authors performed local-density-approximation (LDA) calculations and fit to the two-band model [J.T. Gammel et al., Phys…
Infinite Volume Extrapolations of Finite Cluster Calculations, ---How Correct are These?
S. Mazumdar, F. Guo, D. Guo +2
Extrapolations of numerical data obtained from finite cluster calculations to the infinite volume limit can often give incorrect results. We discuss four separate cases: (a) the in…
Spin-Peierls ground states and frustration in a multi-band Peierls-Hubbard model
H. Roeder, A. R. Bishop, J. Tinka Gammel
We discuss the consequences of including both electron-phonon and electron-electron couplings in multi-band models, focusing on numerical studies of a one-dimensional two-band mode…
Photoinduced charge separation in Q1D heterojunction materials: Evidence for electron-hole pair separation in mixed-halide solids
L. A. Worl, S. C. Huckett, B. I. Swanson +3
Resonance Raman experiments on doped and photoexcited single crystals of mixed-halide complexes (=Pt; =Cl,Br) clearly indicate charge separation: electron polarons prefe…
Electron-Phonon Driven Spin Frustration in Multi-Band Hubbard Models: MX Chains and Oxide Superconductors
J. Tinka Gammel, K. Yonemitsu A. Saxena, A. R. Bishop +1
We discuss the consequences of both electron-phonon and electron-electron couplings in 1D and 2D multi-band (Peierls-Hubbard) models. After briefly discussing various analytic limi…
Extracting Infinite System Properties from Finite Size Clusters: `Phase Randomization/Boundary Condition Averaging'
J. Tinka Gammel, D. K. Campbell, E. Y. Loh
When electron-electron correlations are important, it is often necessary to use exact numerical methods, such as Lanczos diagonalization, to study the full many-body Hamiltonian. U…
Relaxed Excited State Geometries in a Peierls-Hubbard Model for Polyenes
J. Tinka Gammel, D. K. Campbell
Using parameter values relevant to polyacetylene and its finite polyene analogs, we determine, via exact finite size diagonalization of a 1D Peierls-Hubbard model, the relaxed geom…