Benchmark calculations for He2+ and LiH molecules using explicitly correlated Gaussian functions

Abstract Explicitly correlated Gaussian (ECG) functions with carefully optimized non-linear parameters are used to calculate the electronic energies of He2+ and LiH at their equilibrium internuclear distances. The obtained variational upper bounds (−4.99464392 and −8.070538 hartree, respectively) are the lowest reported to date. By extrapolating results obtained with various expansion lengths, the estimations of the Born–Oppenheimer limits are made.

[1]  D. Ceperley,et al.  The dissociation energy of He2 , 1989 .

[2]  J. Noga,et al.  The performance of the explicitly correlated coupled cluster method. I. The four‐electron systems Be, Li−, and LiH , 1995 .

[3]  J. G. Zabolitzky,et al.  Atomic and molecular correlation energies with explicitly correlated Gaussian geminals. I. Second‐order perturbation treatment for He, Be, H2, and LiH , 1983 .

[4]  E. Davidson,et al.  Theoretical Study of the LiH Molecule , 1968 .

[5]  S. M. Rothstein,et al.  Reliable diffusion quantum Monte Carlo , 1988 .

[6]  J. Rychlewski,et al.  Benchmark calculations for two-electron systems using explicitly correlated Gaussian functions , 1995 .

[7]  H. Wallmeier.  Relativistic self-consistent-field calculations with the squared Dirac operator , 1984 .

[8]  H. Schaefer,et al.  An accurate variational wave function for lithium hydride , 1984 .

[9]  Wojciech Cencek,et al.  Accurate relativistic energies of one‐ and two‐electron systems using Gaussian wave functions , 1996 .

[10]  J. Rychlewski,et al.  Many‐electron explicitly correlated Gaussian functions. II. Ground state of the helium molecular ion He+2 , 1995 .

[11]  S. M. Rothstein,et al.  A method for relativistic variational Monte Carlo calculations , 1992 .

[12]  Many-electron correlated exponential wavefunctions. A quantum Monte Carlo application to H2 and He2+ , 1995 .

[13]  P. Knowles,et al.  Microwave electronic spectrum of the He+2 ion , 1995 .

[14]  J. Rychlewski,et al.  Many‐electron explicitly correlated Gaussian functions. I. General theory and test results , 1993 .

[15]  W. T. Zemke,et al.  Spectroscopy and Structure of the Lithium Hydride Diatomic Molecules and Ions , 1993 .

[16]  K. Szalewicz,et al.  High-accuracy Compton profile of molecular hydrogen from explicitly correlated Gaussian wave function , 1979 .

[17]  L. Adamowicz,et al.  A correlated basis set for nonadiabatic energy calculations on diatomic molecules , 1999 .

[18]  Bin Chen,et al.  A simplified released-node quantum Monte Carlo calculation of the ground state of LiH , 1995 .