Measured and calculated double‐ionization energies of 2‐haloethanols

Abstract

Doublecharge-transfer spectroscopy was used to measure the double-ionization energies of the 2-haloethanols FCH,CH,OH, CICH,CH,OH, BrCH,CH,OH and ICH,CH,OH; the values obtained were 30.1 _+ 0.5, 28.1 f 0.5, 27.6 & 0.5 and 26.9 f 0.5 eV, respectively. In addition, the energies were calculated using ab iniiio methods and the GAUSSIAN 90 program package. The measured and calculated values for FCH,CH,OH are in agreement, but for the three other molecules the calculated values are significantly lower than those measured. The discrepancies in the calculations are due mainly to the underestimation of correlation energies by the appropriate MP2 method, which becomes progressively worse with increasing number of electrons in the system.

A relativistic equation-of-motion coupled-cluster investigation of the trends of single and double ionization potentials in the He and Be isoelectronic systems

“…On the other hand, accurate description of the relaxation effects along with the electron correlation effects are essential for explaining multiple ionization processes precisely. Therefore, calculations based on the lower order many-body theories are not reliable enough and may not * Email: h.pathak@ncl.res.in † Corresponding email: bijaya@prl.res.in be able to complement to describe the quality of results that are anticipated from the on-going sophisticated experiments [11]. Kaldor and coworkers have made significant contributions in addressing the simultaneous treatment of relativistic and electron correlation effects using coupled-cluster (CC) methods.…”

Relativistic equation-of-motion coupled-cluster method for the double-ionization potentials of closed-shell atoms

“…15.ac, 31.15.bw, 32. 10.Hq Recent advances in the experimental techniques, such as x-ray free electron laser of Linac Coherent Light sources of SLAC [1,2] and attosecond pulses [3,4], have enabled studies of multi-ionization processes.…”

“…It is well known that not only the electron correlation, but also relaxation effects plays significant role in the accurate description of atomic states. Therefore measurements and calculations based on the lower-order many-body methods do not agree with each other [15]. The equation-of- * h.pathak@ncl.res.in motion coupled-cluster (EOMCC) method [16][17][18] provides a balanced treatment of the electron correlation and relaxation effects to determine the atomic states and also calculating differences of the energies in a direct manner.…”