01580nas a2200193 4500008004100000022001400041245011200055210006900167260007900236300002300315490000700338520082300345100002001168700001801188700002201206700001801228700001601246856012401262 2014 eng d a1050-294700aRelativistic equation-of-motion coupled-cluster method for the ionization problem: application to molecules0 aRelativistic equationofmotion coupledcluster method for the ioni aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMER PHYSICAL SOCcDEC aArticle No. 0625010 v903 a

We report the implementation of the four-component spinor relativistic equation-of-motion (EOM) coupled-cluster method within the single- and double-excitation approximation to calculate the ionization potential of molecules. We have applied this method to calculate vertical ionization potentials of the molecules XH (X = F, Cl, Br, I) along with Cl-2 and Br-2 in their closed-shell configuration. We have also presented intermediate results using the second-order many-body perturbation-theory level in the EOM framework to understand the role of electron correlation. All the calculated values are compared with the available experimental results. Our results are found to be in good agreement with sophisticated experiments, and relative deviation of less than 1% is achieved for all the considered systems.

1 aPathak, Himadri1 aSasmal, Sudip1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-method-ionization-problem-application-001609nas a2200193 4500008004100000022001400041245012300055210006900178260008700247300001100334490000800345520084000353100001801193700002001211700002201231700001801253700001601271856012801287 2015 eng d a0021-960600aCalculation of P,T-odd interaction constant of PbF using Z-vector method in the relativistic coupled-cluster framework0 aCalculation of PTodd interaction constant of PbF using Zvector m a1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScAUG a0841190 v1433 a

The effective electric field experienced by the unpaired electron in the ground state of PbF, which is a potential candidate in the search of electron electric dipole moment due to some special characteristics, is calculated using Z-vector method in the coupled cluster single-and double-excitation approximation with four component Dirac spinor. This is an important quantity to set the upper bound limit of the electron electric dipole moment. Further, we have calculated molecular dipole moment and parallel magnetic hyperfine structure constant (A(parallel to)) of Pb-207 in PbF to test the accuracy of the wavefunction obtained in the Z-vector method. The outcome of our calculations clearly suggests that the core electrons have significant contribution to the ``atom in compound'' properties. (C) 2015 AIP Publishing LLC.

1 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/calculation-pt-odd-interaction-constant-pbf-using-z-vector-method-relativistic-coupled-102036nas a2200193 4500008004100000022001400041245016500055210006900220260007900289300001100368490000700379520123500386100001801621700002001639700002201659700001801681700001601699856012701715 2015 eng d a2469-992600aImplementation of the Z-vector method in the relativistic-coupled-cluster framework to calculate first-order energy derivatives: Application to the SrF molecule0 aImplementation of the Zvector method in the relativisticcoupledc aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMER PHYSICAL SOCcMAR a0305030 v913 a

The molecular dipole moment and magnetic hyperfine-structure constant demand an accurate wave function far from the nucleus and in the near nuclear region, respectively. We, therefore, employ the so-called Z-vector method in the domain of relativistic-coupled-cluster theory to calculate the first-order property of molecular systems in their open-shell ground-state configuration. The implemented method is applied to calculate the molecular dipole moment and parallel component of the magnetic hyperfine-structure constant of the SrF molecule. The results of our calculation are compared with the experimental and other available theoretically calculated values. We are successful in achieving good accordance with the experimental results. The result of our calculation of the molecular dipole moment is in the accuracy of similar to 0.5%, which is clearly an improvement over the previous calculation based on the expectation value method in the four-component coupled-cluster framework [V. S. Prasannaa et al., Phys. Rev. A 90, 052507 (2014)]. Thus, it can be inferred that the Z-vector method can provide an accurate wave function in both the near and far nuclear region, which is evident from our calculated results.

1 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/implementation-z-vector-method-relativistic-coupled-cluster-framework-calculate-first-100625nas a2200169 4500008004100000245009100041210006900132260000800201300002300209490000700232100001800239700002000257700002200277700001800299700001600317856012200333 2015 eng d00aRelativistic extended coupled cluster method for magnetic hyperfine structure constant0 aRelativistic extended coupled cluster method for magnetic hyperf cFEB aArticle No. 0225120 v911 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-extended-coupled-cluster-method-magnetic-hyperfine-structure-constant01296nas a2200181 4500008004100000245013600041210006900177260000800246300001400254490000800268520061000276100001800886700002200904700002200926700001800948700001600966856013200982 2016 eng d00aCalculation of hyperfine structure constants of small molecules using Z-vector method in the relativistic coupled-cluster framework0 aCalculation of hyperfine structure constants of small molecules  cOCT a1671-16750 v1283 aThe Z-vector method in the relativistic coupled-cluster framework is employed to calculate the parallel and perpendicular components of the magnetic hyperfine structure constant of a few small alkaline earth hydrides (BeH, MgH, and CaH) and fluorides (MgF and CaF). We have compared our Z-vector results with the values calculated by the extended coupled-cluster (ECC) method reported in Phys. Rev. A 91 022512 (2015). All these results are compared with the available experimental values. The Z-vector results are found to be in better agreement with the experimental values than those of the ECC values.1 aSasmal, Sudip1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/calculation-hyperfine-structure-constants-small-molecules-using-z-vector-method-relativistic01797nas a2200193 4500008004100000022001400041245011700055210006900172260007900241300001100320490000700331520104800338100001801386700002001404700002201424700001801446700001601464856012301480 2016 eng d a2469-992600aRelativistic coupled-cluster study of RaF as a candidate for the parity- and time-reversal-violating interaction0 aRelativistic coupledcluster study of RaF as a candidate for the  aONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USAbAMER PHYSICAL SOCcJUN a0625060 v933 a

We have employed both the Z-vector method and the expectation-value approach in the relativistic coupled-cluster framework to calculate the scalar-pseudoscalar (S-PS) P, T-odd interaction constant W-s and the effective electric field E-eff experienced by the unpaired electron in the ground electronic state of RaF. Further, the magnetic hyperfine structure constants of Ra-223 in RaF and Ra-223(+) are also calculated and compared with the experimental values wherever available to judge the extent of the accuracy obtained with the employed methods. The outcome of our study reveals that the Z-vector method is superior to the expectation-value approach in terms of accuracy obtained for the calculation of ground-state property. The Z-vector calculation shows that RaF has a high Eeff (52.5 GV/cm) and W-s (141.2 kHz), which makes it a potential candidate for the electric dipole moment of the electron (eEDM) experiment. An estimation of uncertainty associated with our final results is made, and it is found that it lies below 10%.

1 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-coupled-cluster-study-raf-candidate-parity-and-time-reversal-violating01514nas a2200181 4500008004100000245009500041210006900136260000800205300001100213490000900224520088600233100002001119700001801139700002201157700001801179700001601197856011901213 2016 eng d00aRelativistic equation-of-motion coupled-cluster method for the electron attachment problem0 aRelativistic equationofmotion coupledcluster method for the elec cJAN a94-1000 v10763 a

The article considers the successful implementation of relativistic equation-of-motion coupled cluster method for the electron attachment problem (EA-EOMCC) at the level of single- and double- excitation approximation. The implemented relativistic EA-EOMCC method is employed to calculate ionization potential values of alkali metal atoms (Li, Na, K, Rb, Cs, Fr) and the vertical electron affinity values of LiX (X = H, F, Cl, Br), NaY (Y = H, F, Cl) starting from their closed-shell configuration. Both four component and exact two-component calculations are done for all the opted systems. Further, we have shown the effect of spin-orbit interaction considering the atomic systems. The results of our atomic calculations are compared with the values from the NIST database and the results are found to be very accurate (<1%). (C) 2015 Elsevier B.V. All rights reserved.

1 aPathak, Himadri1 aSasmal, Sudip1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-method-electron-attachment-problem01872nas a2200181 4500008004100000245010100041210006900142260000800211300002300219490000800242520121800250100001801468700002001486700002201506700001801528700001601546856012801562 2016 eng d00aSearch for parity and time reversal violating effects in HgH: relativistic coupled-cluster study0 aSearch for parity and time reversal violating effects in HgH rel cMAR aArticle No. 1243070 v1443 a

The high effective electric field (E-eff) experienced by the unpaired electron in an atom or a molecule is one of the key ingredients in the success of electron electric dipole moment (eEDM) experiment and its precise calculation requires a very accurate theory. We, therefore, employed the Z-vector method in the relativistic coupled-cluster framework and found that HgH has a very large E-eff value (123.2 GV/cm) which makes it a potential candidate for the next generation eEDM experiment. Our study also reveals that it has a large scalar-pseudoscalar (S-PS) P, T-violating interaction constant, W-s = 284.2 kHz. To judge the accuracy of the obtained results, we have calculated parallel and perpendicular magnetic hyperfine structure (HFS) constants and compared with the available experimental values. The results of our calculation are found to be in nice agreement with the experimental values. Therefore, by looking at the HFS results, we can say that both E-eff and W-s values are also very accurate. Further, We have derived the relationship between these quantities and the ratio which will help to get model independent value of eEDM and S-PS interaction constant. (C) 2016 AIP Publishing LLC.

1 aSasmal, Sudip1 aPathak, Himadri1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/search-parity-and-time-reversal-violating-effects-hgh-relativistic-coupled-cluster-study01326nas a2200133 4500008004100000245015400041210006900195260000800264300002700272490000700299520074000306100001801046856012801064 2017 eng d00aCalculation of the magnetic hyperfine structure constant of alkali metals and alkaline-earth-metal ions using the relativistic coupled-cluster method0 aCalculation of the magnetic hyperfine structure constant of alka cJUL aArticle Number: 0125100 v963 aThe Z-vector method in the relativistic coupled-cluster framework is used to calculate the magnetic hyperfine structure constant (A(J)) of alkali metals and singly charged alkaline earth metals in their ground state electronic configuration. The Z-vector results are in very good agreement with the experiment. The A(J) values of Li, Na, K, Rb, Cs, Be+, Mg+, Ca+, and Sr+ obtained in the Z-vector method are compared with the extended coupled-cluster results taken from Phys. Rev. A 91, 022512 (2015). The same basis and cutoff are used for the comparison purpose. The comparison shows that the Z-vector method with the single and double approximation can produce a more precise wave function in the nuclear region than the ECC method.1 aSasmal, Sudip uhttps://library.ncl.res.in/content/calculation-magnetic-hyperfine-structure-constant-alkali-metals-and-alkaline-earth-metal01900nas a2200181 4500008004100000022001400041245011100055210006900166260000800235490000700243520124500250100002201495700001801517700002201535700001801557700001601575856012701591 2018 eng d a2469-992600aCorrelation trends in the magnetic hyperfine structure of atoms: a relativistic coupled-cluster case study0 aCorrelation trends in the magnetic hyperfine structure of atoms  cAUG0 v983 a

The role of electron correlation in the hyperfine structure of alkali metals and alkaline earth metal monopositive ions in their ground electronic configuration is investigated using the Z-vector method in a relativistic coupled-cluster regime within the singles and doubles approximation. The systematic effects of core-correlating functions, polarization of core electrons, and high-lying virtual functions on core electrons correlation are studied. The study reveals that the core-correlating function plays a significant role in core polarization and thus is very important for precise calculation of the wave function near the nuclear region. The inner-core electrons (1s-2p) require very high virtual energy functions for proper correlation. Therefore, the all-electron correlation treatment and the inclusion of higher-energy virtual functions are the key factors for precise calculation of the hyperfine structure constant of atoms. Our calculated values are in excellent agreement with the available experimental values, which also implies that the wave function produced by the Z-vector method is accurate enough for further calculation of the parity- and time-reversal symmetry-violating properties in atoms and molecules.

1 aTalukdar, Kaushik1 aSasmal, Sudip1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/correlation-trends-magnetic-hyperfine-structure-atoms-relativistic-coupled-cluster-case01866nas a2200205 4500008004100000022001400041245012500055210006900180260000800249300001100257490000800268520113700276100002001413700001801433700002201451700002201473700001801495700001601513856013101529 2020 eng d a0021-960600aRelativistic double-ionization equation-of-motion coupled-cluster method: application to low-lying doubly ionized states0 aRelativistic doubleionization equationofmotion coupledcluster me cMAR a1043020 v1523 a

This article deals with the extension of the relativistic double-ionization equation-of-motion coupled-cluster (DI-EOMCC) method [H. Pathak et al. Phys. Rev. A 90, 010501(R) (2014)] for the molecular systems. The Dirac-Coulomb Hamiltonian with four-component spinors is considered to take care of the relativistic effects. The implemented method is employed to compute a few low-lying doubly ionized states of noble gas atoms (Ar, Kr, Xe, and Rn) and Cl-2, Br-2, HBr, and HI. Additionally, we presented results with two intermediate schemes in the four-component relativistic DI-EOMCC framework to understand the role of electron correlation. The computed double ionization spectra for the atomic systems are compared with the values from the non-relativistic DI-EOMCC method with spin-orbit coupling [Z. Wang et al. J. Chem. Phys. 142, 144109 (2015)] and the values from the National Institute of Science and Technology (NIST) database. Our atomic results are found to be in good agreement with the NIST values. Furthermore, the obtained results for the molecular systems agree well with the available experimental values.

1 aPathak, Himadri1 aSasmal, Sudip1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVeval, Nayana1 aPal, Sourav uhttps://library.ncl.res.in/content/relativistic-double-ionization-equation-motion-coupled-cluster-method-application-low-lying