01331nas a2200169   4500008004100000022001400041245014200055210006900197260012500266300001100391490000800402520057200410100001900982700001601001700001801017856012601035       2008                        eng d  a0021-960600aCalculation of vibrational energy of molecule using coupled cluster linear response theory in bosonic representation: convergence studies0 aCalculation of vibrational energy of molecule using coupled clus  aCIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScOCT  a1341110 v1293 a<p>Vibrational excited state energies have been calculated using vibrational coupled cluster linear response theory (CCLRT). The method has been implemented on formaldehyde and water molecule. Convergence studies have been shown with varying the cluster operator from S(4) to S(6) as well as the excitation operator from four bosons to six bosons. A good agreement with full configuration interaction results has been observed with S(6) truncation at coupled-cluster method level and six bosonic excitations at CCLRT level. (C) 2008 American Institute of Physics.</p>1 aBanik, Subrata1 aPal, Sourav1 aPrasad, Durga  uhttps://library.ncl.res.in/content/calculation-vibrational-energy-molecule-using-coupled-cluster-linear-response-theory-001578nas a2200169   4500008004100000022001400041245011400055210006900169260007100238300001400309490000600323520089600329100001901225700001601244700001801260856013001278       2010                        eng d  a1549-961800aCalculation of dipole transition matrix elements and expectation values by vibrational coupled cluster method0 aCalculation of dipole transition matrix elements and expectation  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT  a3198-32040 v63 a<p>An effective operator approach based on the coupled cluster method is described and applied to calculate vibrational expectation values and absolute transition matrix elements. Coupled cluster linear response theory (CCLRT) is used to calculate excited states. The convergence pattern of these properties with the rank of the excitation operator is studied. The method is applied to a water molecule. Arponen-type double similarity transformation in extended coupled cluster (ECCM) framework is also used to generate an effective operator, and the convergence pattern of these properties is compared to the normal coupled cluster (NCCM) approach. It is found that the coupled cluster method provides an accurate description of these quantities for low lying vibrational excited states. The ECCM provides a significant improvement for the calculation of the transition matrix elements.</p>1 aBanik, Subrata1 aPal, Sourav1 aPrasad, Durga  uhttps://library.ncl.res.in/content/calculation-dipole-transition-matrix-elements-and-expectation-values-vibrational-coupled-0