01579nas a2200193 4500008004100000022001400041245011200055210006900167260007900236300002300315490000700338520082300345100002001168700001801188700002201206700001801228700001601246856012301262 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 uhttp://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-method-ionization-problem-application-001608nas a2200193 4500008004100000022001400041245012300055210006900178260008700247300001100334490000800345520084000353100001801193700002001211700002201231700001801253700001601271856012701287 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 uhttp://library.ncl.res.in/content/calculation-pt-odd-interaction-constant-pbf-using-z-vector-method-relativistic-coupled-102035nas a2200193 4500008004100000022001400041245016500055210006900220260007900289300001100368490000700379520123500386100001801621700002001639700002201659700001801681700001601699856012601715 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 uhttp://library.ncl.res.in/content/implementation-z-vector-method-relativistic-coupled-cluster-framework-calculate-first-100624nas a2200169 4500008004100000245009100041210006900132260000800201300002300209490000700232100001800239700002000257700002200277700001800299700001600317856012100333 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 uhttp://library.ncl.res.in/content/relativistic-extended-coupled-cluster-method-magnetic-hyperfine-structure-constant01295nas a2200181 4500008004100000245013600041210006900177260000800246300001400254490000800268520061000276100001800886700002200904700002200926700001800948700001600966856013100982 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 uhttp://library.ncl.res.in/content/calculation-hyperfine-structure-constants-small-molecules-using-z-vector-method-relativistic01796nas a2200193 4500008004100000022001400041245011700055210006900172260007900241300001100320490000700331520104800338100001801386700002001404700002201424700001801446700001601464856012201480 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 uhttp://library.ncl.res.in/content/relativistic-coupled-cluster-study-raf-candidate-parity-and-time-reversal-violating01513nas a2200181 4500008004100000245009500041210006900136260000800205300001100213490000900224520088600233100002001119700001801139700002201157700001801179700001601197856011801213 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 uhttp://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-method-electron-attachment-problem01871nas a2200181 4500008004100000245010100041210006900142260000800211300002300219490000800242520121800250100001801468700002001486700002201506700001801528700001601546856012701562 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 uhttp://library.ncl.res.in/content/search-parity-and-time-reversal-violating-effects-hgh-relativistic-coupled-cluster-study01899nas a2200181 4500008004100000022001400041245011100055210006900166260000800235490000700243520124500250100002201495700001801517700002201535700001801557700001601575856012601591 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 uhttp://library.ncl.res.in/content/correlation-trends-magnetic-hyperfine-structure-atoms-relativistic-coupled-cluster-case01789nas a2200181 4500008004100000022001400041245008600055210006900141260000900210300001100219490000700230520118200237100002201419700002201441700001801463700001601481856011001497 2019 eng d a2469-992600aNuclear parity- and time-reversal-symmetry violation in the (HgH)-Hg-201 molecule0 aNuclear parity and timereversalsymmetry violation in the HgHHg20 cMAR  a0325030 v993 a

Investigation of the nuclear magnetic quadrupole moment (MQM) is an excellent way to reveal the new physics in the hadron sector of matter. Therefore, we investigate the violation of parity (P) and time-reversal (T) invariance induced by the MQM of the( 201) Hg nucleus in the HgH molecule, which has been proposed as a very promising candidate for the experimental search of the electric dipole moment of electron [M. G. Kozlov and A. Derevianko, Phys. Rev. Lett. 97, 063001 (2006)]. We report the precise value of the molecular parameter, W-M, associated with the P, T-odd nuclear MQM-electron interaction in (HgH)-Hg-201 using the four-component relativistic coupled-cluster method. This parameter is required to interpret the experimental P, T-odd frequency shift in terms of the MQM of nuclei. Furthermore, the magnetic hyperfine structure (HFS) constants of the molecule are computed at the same level of theory. We also study the role of core-correlating functions and the virtual energy functions in the calculations of the HFS constant and W-M. The most reliable value of W(M )in HgH is obtained as 3.22 x 10 (33) Hz/e cm (2) with an uncertainty of around 6%.

1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/nuclear-parity-and-time-reversal-symmetry-violation-hgh-hg-201-molecule01815nas a2200157 4500008004100000245011000041210006900151260000800220490000800228520121300236100002201449700002201471700001801493700001601511856013001527 2019 eng d00aRelativistic coupled-cluster investigation of parity (P) and time-reversal (T) symmetry violations in HgF0 aRelativistic coupledcluster investigation of parity P and timere cFEB0 v1503 a

We employ the Z-vector method in the four-component relativistic coupled-cluster framework to calculate the parity (P) and time-reversal (T) symmetry violating scalar-pseudoscalar nucleus-electron interaction constant (W-s), the effective electric field (E-eff) experienced by the unpaired electron, and the nuclear magnetic quadrupole moment-electron interaction constant (W-M) in the open-shell ground electronic state of HgF. The molecular frame dipole moment and the magnetic hyperfine structure (HFS) constant of the molecule are also calculated at the same level of theory. The outcome of our study is that HgF has a high value of E-eff (115.9 GV/cm), W-s (266.4 kHz), and W-M (3.59 x 10(33) Hz/e cm(2)), which shows that it can be a possible candidate for the search of new physics beyond the standard model. Our results are in good agreement with the available literature values. Furthermore, we investigate the effect of the basis set and the virtual energy functions on the computed properties. The role of the high-energy virtual spinors is found to be significant in the calculation of the HFS constant and the P,T-odd interaction coefficients. Published under license by AIP Publishing.

1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/relativistic-coupled-cluster-investigation-parity-p-and-time-reversal-t-symmetry-violations01377nas a2200181 4500008004100000022001400041245010800055210006900163260000800232300001100240490000800251520073600259100002200995700002201017700001801039700001601057856012201073 2020 eng d a0021-960600aElectronic structure parameter of nuclear magnetic quadrupole moment interaction in metal monofluorides0 aElectronic structure parameter of nuclear magnetic quadrupole mo cNOV a1843060 v1533 a

The electronic structure parameter (W-M) of the nuclear magnetic quadrupole moment (MQM) interaction in numerous open-shell metal monofluorides (viz., MgF, CaF, SrF, BaF, RaF, and PbF) is computed in the fully relativistic coupled-cluster framework. The electron-correlation effects are found to be very important for the precise calculation of W-M in the studied molecular systems. The molecular MQM interaction parameter scales nearly as Z(2) in the alkaline earth metal monofluorides, where Z is the nuclear charge of metal. Our study identifies (RaF)-Ra-223 as a good candidate for the experimental search of the nuclear MQM, which can help unravel the physics beyond the standard model in the hadron sector of matter.

1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/electronic-structure-parameter-nuclear-magnetic-quadrupole-moment-interaction-metal01798nas a2200217 4500008004100000022001400041245007200055210006900127260000800196300001100204490000700215520109000222653004301312653002501355653002501380100002201405700002201427700001801449700001601467856009701483 2020 eng d a0953-407500aRelativistic coupled-cluster study of BaF in search of CP violation0 aRelativistic coupledcluster study of BaF in search of CP violati cJUL a1351020 v533 a

BaF is one of the potential candidates for the experimental search of the electric dipole moment of the electron (eEDM). The NL-eEDM collaboration is building a new experimental set up to measure the eEDM using the BaF molecule (The NL-eEDM collaboration, 2018 Eur. Phys. J. D 72: 197). To analyze the results of such an experiment, one would require the accurate value of the molecular P, T-odd interaction parameters that cannot be measured from any experiment. In this work, we report the precise value of the P, T-odd interaction parameters of the BaF molecule obtained from the four-component relativistic coupled-cluster calculations. We also calculate the hyperfine structure (HFS) constants of the same molecule to assess the reliability of the reported molecular parameters. The calculated HFS constants show good agreement with the available experimental values. Further, the systematic effects of electron-correlation along with the roles of inner-core electrons and the virtual energy functions in the calculation of the studied properties of BaF are investigated.

10aelectric dipole moment of the electron10aelectron-correlation10aRelativistic effects1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/relativistic-coupled-cluster-study-baf-search-cp-violation01865nas a2200205 4500008004100000022001400041245012500055210006900180260000800249300001100257490000800268520113700276100002001413700001801433700002201451700002201473700001801495700001601513856013001529 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 uhttp://library.ncl.res.in/content/relativistic-double-ionization-equation-motion-coupled-cluster-method-application-low-lying01560nas a2200181 4500008004100000022001400041245011000055210006900165260000900234300001100243490000800254520091100262100002201173700002201195700001801217700001601235856012701251 2020 eng d a2469-992600aRole of electron correlation in the P, T-odd effects of CdH: a relativistic coupled-cluster investigation0 aRole of electron correlation in the P Todd effects of CdH a rela cMAR  a0325050 v1013 a

We investigate the parity (P) and time-reversal (T) symmetry violating effects in the CdH molecule and perform the relativistic coupled-cluster calculation of the molecular parameters-E-eff, W-s, and W-M-related to the electric dipole moment of electron (eEDM) interaction, the scalar-pseudoscalar (S-PS) nucleus-electron neutral current coupling, and the nuclear magnetic quadrupole moment (MQM) interaction with electrons, respectively. We also compute the molecular dipole moment and the magnetic hyperfine structure coupling constant of CdH. The values of E-eff, W-s, and W-M obtained by us in the said molecule are 12.2 GV/cm, 14.0 kHz, and 0.82 x 10(33) Hz/e cm(2), respectively, within an uncertainty of 10%. Furthermore, we study the trend of electron-correlation in the computed properties of CdH and that of the P, T-odd parameters in the group-12 monohydrides (i.e., ZnH, CdH, and HgH).

1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/role-electron-correlation-p-t-odd-effects-cdh-relativistic-coupled-cluster-investigation01943nas a2200181 4500008004100000022001400041245011500055210006900170260000800239300001400247490000700261520128600268100002201554700002201576700001801598700001601616856012901632 2025 eng d a1549-961800aRelativistic extended-coupled-cluster calculations of P , T -odd sensitivity parameters for diatomic molecules0 aRelativistic extendedcoupledcluster calculations of P T odd sens cMAY a5481-54890 v213 a

We demonstrate the first application of the four-component relativistic extended-coupled-cluster (ECC) method, a variational approach, to determine the P , T -odd molecular electronic structure parameters necessary for high-precision spectroscopic measurements on ultracold molecules. We calculate the P , T -odd sensitivity parameters for two moderately heavy, laser-coolable diatomic molecules (SrH and SrF), as well as two relatively lighter open-shell molecules (CaH and CaF) in their ground electronic state, 2 Sigma 1/2. The hyperfine structure constants of 87Sr in the SrF and SrH molecules are also computed and compared with available experimental results to assess the accuracy of our calculations. Furthermore, we examine the roles of electron correlation, relativity, basis set, and virtual spinors in ECC calculations of the sensitivity parameters. Our study reveals that the ECC method is a reliable technique for studying P , T -odd properties of diatomic molecules such as CaH, CaF, SrH and SrF, yielding results in very good agreement with those obtained using two widely employed analytic approaches: the Z-vector technique and the linear expectation-value method within the relativistic single-reference coupled-cluster singles and doubles framework.

1 aTalukdar, Kaushik1 aNayak, Malaya, K.1 aVaval, Nayana1 aPal, Sourav uhttp://library.ncl.res.in/content/relativistic-extended-coupled-cluster-calculations-p-t-odd-sensitivity-parameters-diatomic