02126nas a2200217   4500008004100000022001400041245015500055210006900210260007300279300001100352490000800363520128100371653001501652653001401667653001901681653001801700653002501718100001901743700001601762856013001778       2009                        eng d  a0166-128000aIonization potential and structure relaxation of adenine, thymine, guanine and cytosine bases and their base pairs: a quantification of reactive sites0 aIonization potential and structure relaxation of adenine thymine  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY  a96-1020 v9023 a<p>We present density functional theory (DFT) calculations using B3LYP/6-31++G** method to show relaxation in geometry of base pairs on cation radical formation. The changes in hydrogen bond length and angles show that in the cationic radical form the structure of the base pairs relaxes due to the distribution of charge. According to a recent study. it has been found that, upon excitation hole transfer from base to sugar occurs which results in sugar radical formation and leads to strand breakage 145] [A. Kumar, M.D. Sevilla, J. Phys. Chem. B 110 (2006) 24181]. One hydrogen bond increases, while the other decreases in Adenine-Thymine (AT) base pair and in case of Guanine-Cytosine (GC) base pair. one bond increases and other two decrease. Same is the case with bond angles for both the base pairs. Analysis of the electron density map of Singly Occupied Molecular Orbital (SOMO) reveals that electron is transferred mainly from adenine and guanine bases in the cationic radical formation of AT and CC base pair, respectively. The reactive sites of bases have been analyzed using condensed Fukui functions in a relaxed and frozen core approximation. The effects of relaxation on the reactivity indices are also analyzed. (C) 2009 Elsevier B.V. All rights reserved.</p>10aBase-pairs10aDNA bases10aFukui function10aH-bond length10aIonization potential1 aMishra, Deepti1 aPal, Sourav  uhttps://library.ncl.res.in/content/ionization-potential-and-structure-relaxation-adenine-thymine-guanine-and-cytosine-bases-001372nas a2200205   4500008004100000022001400041245009300055210006900148260000800217300001100225490000800236520069000244653001300934653002500947653001800972100002700990700001801017700001601035856011501051       2018                        eng d  a0020-760800aLower scaling approximation to EOM-CCSD: a critical assessment of the ionization problem0 aLower scaling approximation to EOMCCSD a critical assessment of   cJUL  ae255940 v1183 a<p>In this article, we investigate the performance of different approximate variants of the EOM-CCSD method for calculation of ionization potential (IP), as compared to EOM-CCSDT reference values. None of the lower scaling approximations to the EOM-CCSD method give a consistent performance for valence, inner valence, and core ionization, favoring one, or the other depending on the nature of the approximation used. The parent EOMIP-CCSD method gives superior performance for valence IP but can show large errors for inner valence and core ionization. The problem is particularly severe for core-ionization, where even the EOMIP-CCSDT method cannot provide quantitative accuracy.</p>10aEOM-CCSD10aIonization potential10alower scaling1 aDutta, Achintya, Kumar1 aVaval, Nayana1 aPal, Sourav  uhttps://library.ncl.res.in/content/lower-scaling-approximation-eom-ccsd-critical-assessment-ionization-problem