01720nas a2200253 4500008004100000022001400041245005800055210005800113260009200171300001200263490000700275520083500282653003001117653003201147653002001179653003901199653004701238653003501285100001501320700001401335700001401349700001201363856009101375 2014 eng d a0144-235X00aCoupled cluster methods for autoionisation resonances0 aCoupled cluster methods for autoionisation resonances a4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLANDbTAYLOR & FRANCIS LTDcSEP a397-4250 v333 a

The quantum chemical calculation of autoionisation resonances in many-electron systems is a highly challenging task due to the ionisation continuum involved. Recently, advances were reported where conventionally used ab initio codes can be employed to compute autoionisation resonances. This is made possible by the use of analytical continuation tools such as complex scaling and complex absorbing potential (CAP) in the electronic structure codes. We review the formulation and the use of complex scaling and CAP in coupled cluster methods for the electron correlated calculation of energy position and autoionisation decay rate of resonance states. The application of analytically continued coupled cluster method for the correlated calculation of interatomic or intermolecular Coulombic decay process is also discussed.

10aautoionisation resonances10acomplex absorbing potential10acomplex scaling10aequation-of-motion coupled cluster10aFock space multi-reference-coupled cluster10aintermolecular Coulombic decay1 aSajeev, Y.1 aGhosh, A.1 aVaval, N.1 aPal, S. uhttps://library.ncl.res.in/content/coupled-cluster-methods-autoionisation-resonances-001731nas a2200169 4500008004100000245013600041210006900177260000800246490000800254520109400262100001501356700001501371700001801386700001401404700001201418856013101430 2016 eng d00aRelativistic equation-of-motion coupled-cluster method using open-shell reference wavefunction: application to ionization potential0 aRelativistic equationofmotion coupledcluster method using opensh cAUG0 v1453 aThe open-shell reference relativistic equation-of-motion coupled-cluster method within its four-component description is successfully implemented with the consideration of single- and double- excitation approximations using the Dirac-Coulomb Hamiltonian. At the first attempt, the implemented method is employed to calculate ionization potential value of heavy atomic (Ag, Cs, Au, Fr, and Lr) and molecular (HgH and PbF) systems, where the effect of relativity does really matter to obtain highly accurate results. Not only the relativistic effect but also the effect of electron correlation is crucial in these heavy atomic and molecular systems. To justify the fact, we have taken two further approximations in the four-component relativistic equation-of-motion framework to quantify how the effect of electron correlation plays a role in the calculated values at different levels of theory. All these calculated results are compared with the available experimental data as well as with other theoretically calculated values to judge the extent of accuracy obtained in our calculations. 1 aPathak, H.1 aSasmal, S.1 aNayak, M., K.1 aVaval, N.1 aPal, S. uhttps://library.ncl.res.in/content/relativistic-equation-motion-coupled-cluster-method-using-open-shell-reference-wavefunction01405nas a2200157 4500008004100000245012600041210007300167260000800240520078100248100001501029700001701044700001601061700001401077700001201091856014401103 2017 eng d00aElectron–nucleus scalar–pseudoscalar interaction in PbF: Z-vector study in the relativistic coupled-cluster framework0 aElectron–nucleus scalar–pseudoscalar interaction in PbF Zvector  cMAY3 a

The scalar–pseudoscalar interaction constant of PbF in its ground state electronic configuration is calculated using the Z-vector method in the relativistic coupled-cluster framework. The precise calculated value is very important to set upper bound limit on (Formula presented.)-odd scalar–pseudoscalar interaction constant, ks, from the experimentally observed (Formula presented.)-odd frequency shift. Further, the ratio of the effective electric field to the scalar–pseudoscalar interaction constant is also calculated which is required to get an independent upper bound limit of electric dipole moment of electron, de, and ks and how these (de and ks) are interrelated is also presented here. © 2017 Informa UK Limited, trading as Taylor & Francis Group

1 aSasmal, S.1 aTalukdar, K.1 aNayak, M.K.1 aVaval, N.1 aPal, S. uhttps://library.ncl.res.in/content/electron%E2%80%93nucleus-scalar%E2%80%93pseudoscalar-interaction-pbf-z-vector-study-relativistic-coupled02065nas a2200145 4500008004100000022001400041245011200055210006900167260000800236490000700244520151500251100001401766700001401780856012501794 2023 eng d a1439-423500aEffect of protonation and deprotonation on electron transfer mediated decay and interatomic coulombic decay0 aEffect of protonation and deprotonation on electron transfer med cJAN0 v243 a

Electronically excited atoms or molecules in an environment are often subject to interatomic/intermolecular Coulombic decay (ICD) and/or electron transfer mediated decay (ETMD) mechanisms. A few of the numerous variables that can impact these non-radiative decay mechanisms include bond distance, the number of nearby atoms or molecules, and the polarisation effect. In this paper, we have studied the effect of protonation and deprotonation on the ionization potential (IP), double ionization potential (DIP), and lifetime (or decay width) of the temporary bound state in these non-radiative decay processes. We have chosen LiH-NH3 and LiH-H2O as test systems. The equation of motion coupled cluster singles and doubles method augmented by complex absorbing potential (CAP-EOM-CCSD) has been used in calculating the energetic position of the decaying state and the system's decay rate. Deprotonation of LiH-NH3/LiH-H2O either from the metal center (LiH) or from ammonia/water lowers the IP and DIP compared to the neutral systems. In contrast, protonation increases these quantities compared to neutral systems. The protonation closes the inner valence state relaxation channels for ICD/ETMD. For example, the decay of the O-2s/N-2s state stops in protonated systems (LiH2+-H2O, LiH2+-NH3, and LiH-NH4+). Our study also shows that the efficiency, i. e., the rate of ICD/ETMD, can be altered by protonation and deprotonation. It is expected to have implications for chemical and biological systems.

1 aKumar, R.1 aVaval, N. uhttps://library.ncl.res.in/content/effect-protonation-and-deprotonation-electron-transfer-mediated-decay-and-interatomic