01653nas a2200169   4500008004100000022001400041245008500055210006900140260007100209300001400280490000700294520101700301100002701318700001801345700001601363856010401379       2015                        eng d  a1549-961800aEOMIP-CCSD(2)*: an efficient method for the calculation of ionization potentials0 aEOMIPCCSD2 an efficient method for the calculation of ionization  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN  a2461-24720 v113 a<p>A new approximation within the domain of EOMIP-CC method is proposed. The proposed scheme is based on the perturbative truncation of the similarity transformed effective Hamiltonian matrix. We call it the EOMIP-CCSD(2)* method, which scales as noniterative N-6 and its storage requirement is very less, compared to the conventional EOMIP-CCSD method. The existing EOMIP-CCSD(2) method has a tendency to overestimate the ionization potential (IP) values. On the other hand, our new strategy corrects for the problem of such an overestimation, which is evident from the excellent agreement achieved with the experimental values. Furthermore, not only the ionization potential but also geometry and IR frequencies of problematic double radicals are estimated correctly, and the results are comparable to the CCSD(T) method, obviously at lesser computational cost. The EOMIP-CCSD(2)* method works even for the core ionization and satellite IP, where the earlier EOMIP-CCSD(2) approximation dramatically fails.</p>1 aDutta, Achintya, Kumar1 aVaval, Nayana1 aPal, Sourav  uhttps://library.ncl.res.in/content/eomip-ccsd2-efficient-method-calculation-ionization-potentials-1