Relaxation energies and excited state structures of poly(para-phenylene)

We investigate the relaxation energies and excited state geometries of the light emitting polymer, poly(para-phenylene). We solve the Pariser-Parr-Pople-Peierls model using the density matrix renormalization group method. We find that the lattice relaxation of the dipole-active $1^1B_{1u}^-$ state is quite different from that of the $1^3B_{1u}^+$ state and the dipole-inactive $2^1A_g^+$ state. In particular, the $1^1B_{1u}^-$ state is rather weakly coupled to the lattice and has a rather small relaxation energy ca. 0.1 eV. In contrast, the $1^3B_{1u}^+$ and $2^1A_g^+$ states are strongly coupled with relaxation energies of ca. 0.5 and ca. 1.0 eV, respectively. By analogy to linear polyenes, we argue that this difference can be understood by the different kind of solitons present in the $1^1B_{1u}^-$, $1^3B_{1u}^+$ and $2^1A_g^+$ states. The difference in relaxation energies of the $1^1B_{1u}^-$ and $1^3B_{1u}^+$ states accounts for approximately one-third of the exchange gap in light-emitting polymers.Comment: Submitted to Physical Review

Perturbative QCD and Tau Decay

Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter $A_\tau$ that determines that angular distribution of the total hadron momentum in the decay of a polarized tau. It should be possible to measure $A_\tau$ accurately using existing data from LEP. Reliable estimates of theoretical errors are essential in order to determine whether a given observable is sufficiently inclusive to be calculated using perturbative methods. The theoretical uncertainties due to higher orders in $\alpha_s$ can be estimated using recent calculations to all orders in the large-$(33-2N_f)$ limit. These estimates indicate that tau decay data can be used to determine $\alpha_s(M_Z)$ to a precision of 2% or better.Comment: 9 pages, LaTeX with espcrc2.sty, invited talk presented at the TAU 96 Workshop, Estes Park, Colorado, in September 199

An Examination of Estimated BMI and Perceived Wellness among Students at a Midsized Midwest University

Health is complex and the perception of individual wellness can be influenced by various factors. Students at a Midwestern university estimated their BMI, completed the Perceived Wellness Survey, and had their BMI calculated. Measured BMI was significantly higher than estimated [F(2,155) = 62.03, p = 0.001]. Associations existed between the measured constructs of psychological (r = -0.231; p = 0.004), spiritual (r = 0.248; p = 0.002), and estimated BMI. Data indicates that perceived body composition is related to wellness. False perception of body composition could lead to wellness deficiencies