Relativistic and correlation effects in atoms

This review article deals with some case studies of relativistic and correlation effects in atomic systems. After a brief introduction to relativistic many-electron theory, a number of applications ranging from correlation energy to parity non-conservation in atoms are considered. There is a special emphasis on relativistic coupled-cluster theory as most of the results presented here are based on it.Comment: Review article, 4 eps figures, latex 2

Relativistic Coupled-Cluster Theory of Atomic Parity Nonconservation: Application to 137^{137}Ba+^+

We report the result of our {\it ab initio} calculation of the $6s ^2S_{1/2} \to 5d ^2D_{3/2}$ parity nonconserving electric dipole transition amplitude in $^{137}\text{Ba}^+$ based on relativistic coupled-cluster theory. Considering single, double and partial triple excitations, we have achieved an accuracy of less than one percent. If the accuracy of our calculation can be matched by the proposed parity nonconservation experiment in Ba$^+$ for the above transition,then the combination of the two results would provide an independent non accelerator test of the Standard Model of particle physics.Comment: 4 pages, 1 figure, Submitted to PR

Study of HgOH to Assess Its Suitability for Electron Electric Dipole Moment Searches

In search of suitable molecular candidates for probing the electric dipole moment (EDM) of the electron (de), a property that arises due to parity and time-reversal violating (P,T-odd) interactions, we consider the triatomic mercury hydroxide (HgOH) molecule. The impetus for this proposal is based on previous works on two systems: the recently proposed ytterbium hydroxide (YbOH) experiment [Phys. Rev. Lett. 119, 133002 (2017)] that demonstrates the advantages of polyatomics for such EDM searches, and the finding that mercury halides provide the highest enhancement due to de compared to other diatomic molecules [Phys. Rev. Lett. 114, 183001 (2015)]. We identify the ground state of HgOH as being in a bent geometry, and show that its intrinsic EDM sensitivity is comparable to the corresponding value for YbOH. Along with the theoretical results, we discuss plausible experimental schemes for an EDM measurement in HgOH. Furthermore, we provide pilot calculations of the EDM sensitivity for de for HgCH₃ and HgCF₃, that are natural extensions of HgOH

Relativistic coupled cluster calculations of the energies for rubidium and cesium atoms

Ionization potentials and excitation energies of rubidium and cesium atoms are computed using the relativistic coupled cluster (CC) method. The effect of electron correlations on the ground and excited state properties is investigated using different levels of CC approximations and truncation schemes. The present work demonstrates that the even-parity channel truncation scheme produces results almost as accurate as obtained from the all-parity channel approximation scheme at a reduced computational cost. The present study also indicates that for a given basis the linearized CC method tends to overestimate the ground and excited state properties compared to the full CC method

Ab initio determination of the lifetime of the 62P3/26^2P_{3/2} state f or 207Pb+^{207}Pb^+ by relativistic many-body theory

Relativistic coupled-cluster(RCC) theory has been employed to calculate the life time of the $6 ^2P_{3/2}$ state of single ionized lead($^{207}Pb$) to an accurac y of 3% and compared with the corresponding value obtained using second order r elativistic many-body perturbation theory(RMBPT). This is one of the very few ap plications of this theory to excited state properties of heavy atomic systems. C ontributions from the different electron correlation effects are given explicitl y

From menarche to menopause: A population-based assessment of water, sanitation, and hygiene risk factors for reproductive tract infection symptoms over life stages in rural girls and women in India.

Women face greater challenges than men in accessing water, sanitation, and hygiene (WASH) resources to address their daily needs, and may respond to these challenges by adopting unsafe practices that increase the risk of reproductive tract infections (RTIs). WASH practices may change as women transition through socially-defined life stage experiences, like marriage and pregnancy. Thus, the relationship between WASH practices and RTIs might vary across female reproductive life stages. This cross-sectional study assessed the relationship between WASH exposures and self-reported RTI symptoms in 3,952 girls and women from two rural districts in India, and tested whether social exposures represented by reproductive life stage was an effect modifier of associations. In fully adjusted models, RTI symptoms were less common in women using a latrine without water for defecation versus open defecation (Odds Ratio (OR) = 0.69; Confidence Interval (CI) = 0.48, 0.98) and those walking shorter distances to a bathing location (OR = 0.79, CI = 0.63, 0.99), but there was no association between using a latrine with a water source and RTIs versus open defecation (OR = 1.09; CI = 0.69, 1.72). Unexpectedly, RTI symptoms were more common for women bathing daily with soap (OR = 6.55, CI = 3.60, 11.94) and for women washing their hands after defecation with soap (OR = 10.27; CI = 5.53, 19.08) or ash/soil/mud (OR = 6.02; CI = 3.07, 11.77) versus water only or no hand washing. WASH practices of girls and women varied across reproductive life stages, but the associations between WASH practices and RTI symptoms were not moderated by or confounded by life stage status. This study provides new evidence that WASH access and practices are associated with self-reported reproductive tract infection symptoms in rural Indian girls and women from different reproductive life stages. However, the counterintuitive directions of effect for soap use highlights that causality and mechanisms of effect cannot be inferred from this study design. Future research is needed to understand whether improvements in water and sanitation access could improve the practice of safe hygiene behaviors and reduce the global burden of RTIs in women

{\it Ab initio} calculations of forbidden transition probabilities and lifetimes of low-lying states in V4+^{4+}

Electric quadrupole (E2) and magnetic dipole (M1) transition amplitudes among the low-lying states of quadruply ionized vanadium V$^{4+}$, important in various field of experimental and astrophysics are presented very accurately. Most of these results are reported for the first time in the literature. Relativistic coupled-cluster theory with single, double and leading triple excitations has been employed for these calculations. Estimation of different correlation effects arising through the above formalism have been highlighted by studying core and valence electrons excitations to the excited states. The lifetime of the first excited $D$- state is found to be long.Comment: 16 pages in pdf outpu