Effects of the Nearest-Neighbour Coulomb Interactions on the Ground State of the Periodic Anderson Model

The magnetic and non-magnetic ground states of the periodic Anderson model with Coulomb interaction between $f$-electrons on the nearest-neighbour(NN) sites are investigated using a variational method, which gives exact calculation of the expectation values in the limit of infinite dimensions. It is shown that for a critical value of NN Coulomb interactions the magnetic ground state of the periodic Anderson model in the Kondo regime is unstable. Factors in terms of the physical processes responsible for instability of the magnetic ground state are also discussed. Our study indicates the importance of the NN Coulomb interactions for correlated two band models.Comment: RevTeX, 6 pages, 5 figures, to appear in Phys. Rev.

Alternative to Gutzwiller's approach

An efficient variational procedure to calculate the ground-state properties of the particle-hole symmetric periodic Anderson model is presented. Expectation values are calculated by using an approximate scheme. It is shown that the ground-state energy calculated with the one-site approximation, which essentially is a single-site mean-field approximation, is identical to the corresponding energy obtained by the well-known Gutzwiller wave function using the Gutzwiller approximation. The two-site approximation, in which intersite correlations are explicitly included, is shown to be a better approximation than the Gutzwiller approximation

Transport through a coupled quantum dot system: role of interdot interactions

The coupled double quantum dot system is modeled by a two impurity Anderson-type Hamiltonian and interdot Coulomb interaction is included. The conductance of this system is calculated using a nonequilibrium Green's-function formalism. We have evaluated conductance, peak splitting, and amplitude of conductance peaks as a function of Fermi energy for various values of parameters of the model Hamiltonian. It is demonstrated that an interdot interaction whose strength is assumed to be 10% of the ondot Coulomb interaction produces significant changes in the conductance in a coupled double quantum dot system

Role of defects in transport through a quantum dot single electron transistor

The effect of a single dotlike defect on the transport through a quantum dot single electron transistor weakly coupled to external leads is studied. It is found that the conductance profile is changed significantly by the quantum mechanical tunneling between the dot and the defect and the interactions between them, both of which are dependent on the distance between the dot and the defect, as also by the morphology of the defect. In particular, we find that even a very small strength of interdot interaction has a major influence on the transport and must be taken into account in device fabrication

Assessment of psychiatric morbidity in postmenopausal women

Background:Menopause is one of the crucial phases of women’s life. Although the fact has been ignored or hidden for a long time, it is now clearly established that this is a difficult time of life due to high frequency of physical and psychological disorders which affect majority of the women. The present study was conducted to assess psychiatric morbidity in postmenopausal women attending gynaecological outdoor patient department.Materials & Methods: 50 consecutive postmenopausal women attending Gynae OPD in New Medical College hospital, Kota constituted the sample of study whereas 50 randomly postmenopausal women who were not attending Gynae OPD, who had not undergone surgical menopause (Post Hysterectomy). preferably relatives of postmenopausal patients, constituted the control group.Results: Maximum patients 32 (64%) in study group and 33 (66%) were in age group 40-45 years. Past history was seen in 8 in study group and 2 in control group. GHQ score >4 was seen in 26 in study group and 40 in control group. 7 in study and 4 in control group had Mixed anxietydepressivedisorder. Severe depression was seen in 3 in study and 0 in control group. Conclusion: 42% of the patients from the study group received psychiatric diagnosis according to the ICD-10. Mild depression was present in 2% patients, moderate depression in 8% and severe depression in 6% patients

Phosphorus adsorption using chemical and metal chloride activated biochars: Isotherms, kinetics and mechanism study

Efficient treatment of nutrient-rich wastewater is of paramount importance for protecting the ecosystem. In this work, an efficient, abundant, and eco-friendly adsorbent was derived from biochar and employed for phosphorus (P) adsorption. The key factors influencing the P removal efficiency of the activated biochar, including P concentration, pH, dosage, temperature, adsorption time, and influence of co-existing ion type, were investigated. Maximum P adsorption percentage (100%) was obtained with 10 mg/L and zinc chloride activated biochar (BC–Zn) compared to the other activated biochars. Results show that by increasing the P concentration from 5 to 200 mg/L, the phosphorus adsorption capacity increases from 0.13 to 10.4 mg/g biochar. Isotherms and kinetic studies further show that the P adsorption follows the Langmuir and quasi-second-order kinetic models. The mechanistic investigation demonstrated that P adsorption occurred by precipitation reaction. Furthermore, P desorption has been studied at different time intervals to understand the P release rate after adsorption