The multideterminental-DFT approach was performed in order to calculate the Jahn-Teller (JT) parameters for the JT active molecules. Within the harmonic approximation the JT distortion can be analysed as a linear combination of all totally symmetric normal modes in any of the low symmetry minimum energy conformation, which allows to calculate the Intrinsic Distortion Path (IDP), exactly from th...

Relations between the total β+ Gamow-Teller (GT+) strength and the E2 strength are further examined. It is found that in shell-model calculations for N =Z nuclei, in which changes in deformation are induced by varying the single-particle energies, the total GT+ or GT− strength decreases monotonically with increasing values of the B(E2) from the ground state to the first excited J π =2 + state. ...

We propose numerical simulations of the Ashkin-Teller model as a foil for theoretical techniques for studying very weakly first-order phase transitions in three dimensions. The Ashkin-Teller model is a simple two-spin model whose parameters can be adjusted so that it has an arbitrarily weakly first-order phase transition. In this limit, there are quantities characterizing the firstorder transit...

Infrared spectra of a K4C60 single-phase thin film have been measured between room temperature and 20 K. At low temperatures, the two high-frequency T1u modes appear as triplets, indicating a static D2h crystal-field stabilized Jahn-Teller distortion of the C60 42 anions. The T1u(4) mode changes into a known doublet above 250 K, a pattern which could have three origins: a dynamic Jahn-Teller ef...

B. Alex Brown iVational Superconducting Cyclotron Laboratory and Department of Physics and AstronomyM, ichigan State University, East Lansing, Michigan 48824-1321 (Received 18 February 1992) Calculations are presented for the Gamow-Teller strength distribution in the P+ decay of "Ca and compared to results extracted from recent beta decay data and from (p,n) data on the analog nucleus Cl. The s...

Jahn-Teller (JT) electron-phonon coupling effects in the colossal magnetoresistance perovskite compounds La1−xAxMnO3 are investigated. Electronelectron correlations between two degenerate Mn eg orbitals are studied in the Gutzwiller approximation. The static JT distortion and antiadiabatic polaron effects are studied in a modified Lang-Firsov approximation. We find that (i) the electron or hole...

The 11B(3He, t), 11B(d, d), and 11B(p, p) reactions were measured at forward scattering angles including 0 to study the isovector and isoscalar spin-flip M1 strengths in 11B. The measured 11B(3He, t) cross sections were compared with the results of the distorted-wave impulseapproximation (DWIA) calculation, and the Gamow-Teller (GT) strengths for low-lying states in 11C were determined. The GT ...

Differential cross sections for the (p, n) reaction on ‘*,%r and 57,5XFe have been measured for angles up to Slirh = X0.5” and 14.6”, respectively, using 120 MeV protons. The observed angular distributions are used to evaluate the location and strength of Gamow-Teller resonances. A shell-model calculation of this strength distribution is presented and compared with the experimental results. The...

The laser excited, jet-cooled Ã2A′′ 2 − X̃2E′′ 1 electronic spectrum of the cyclopentadienyl radical yields detailed information about the vibronic structure of both its à and X̃ states. A straight-forward assignment of the à vibronic structure is presented. The X̃ state vibronic structure reveals a comprehensive picture of the Jahn-Teller distortion of its potential energy surface. The molecular ...

We study supervised learning and generalisation in coupled perceptrons trained on-line using two learning scenarios. In the first scenario the teacher and the student are independent networks and both are represented by an Ashkin-Teller perceptron. In the second scenario the student and the teacher are simple perceptrons but are coupled by an Ashkin-Teller type four-neuron interaction term. Exp...