ASPIN: An all spin scattering code for atom-molecule rovibrationally inelastic cross sections

Abstract We present in this work a new computational code for the quantum calculation of integral cross sections for atom–molecule (linear) scattering processes. The atom is taken to be structureless while the molecule can be in its singlet, doublet, or triplet spin states and can be treated as either a rigid rotor or a rovibrational target. All the relevant state-to-state integral cross sections, and their sums over final states, can be calculated with the present code, for which we also describe in detail the various component routines. Program summary Program title: ASPIN Catalogue identifier: AEBO_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEBO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 99 596 No. of bytes in distributed program, including test data, etc.: 1 267 615 Distribution format: tar.gz Programming language: Fortran/MPI Computer: AMD OPTERON COMPUTING SYSTEMS, model TYAN GX28 (B2882) Operating system: SuSE LINUX Professional 9 RAM: 128 GB Classification: 2.6 External routines: LAPACK/BLAS Nature of problem: Scattering of a diatomic molecule in its Σ 1 , Σ 2 , or Σ 3 spin states with an atom in its S 1 state. Partial and integral cross sections. Solution method: The coupled channel equations that describe the scattering process are solved through the propagation of the reactance K matrix employing a modification of the Variable Phase Method [1–3]. Restrictions: Depending on the vib-rotational base used the problem may or may not fit into available RAM memory because all the runtime relevant quantities are stored on RAM memory instead of on disk. Additional comments: Both serial and parallel implementations of the program are provided. The CPC Librarian was not able to successfully run the parallel version. Running time: For simple and converged calculations a usual running time is in the order of a few minutes in the computer mentioned above, being shorter for the singlet and longer for the triplet. References: [1] F. Calogero, Variable Phase Approach to Potential Scattering, New York, 1967. [2] A. Degasperis, Il Nuovo Cimento 34 (1964) 1667. [3] C. Zemach, Il Nuovo Cimento 33 (1964) 939.

[1]  R. Decarvalho,et al.  Magnetic trapping of calcium monohydride molecules at millikelvin temperatures , 1998, Nature.

[2]  D. Secrest,et al.  The generalized log‐derivative method for inelastic and reactive collisionsa) , 1983 .

[3]  M. Alexander,et al.  Asymptotic behaviour of the Percival-Seaton coefficients and implications for molecular collisions , 1976 .

[4]  A. Arthurs,et al.  The theory of scattering by a rigid rotator , 1960, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[5]  C. Williams,et al.  Molecules at Rest , 2000, Science.

[6]  J. Doyle,et al.  Chemical physics: Molecules are cool , 1999, Nature.

[7]  B. Levi.  Hot Prospects for Ultracold Molecules , 2000 .

[8]  E. Bodo,et al.  Rotational cooling efficiency upon molecular ionization: the case of Li2(a3Σu+) and Li2+(X2Σg+) interacting with 4He , 2007 .

[9]  P. Ziemann,et al.  Kinetic study of neutral lead cluster reactions , 1993 .

[10]  M. L. Dourneuf,et al.  The variable-phase method in multichannel electron-atom or electron-ion scattering , 1977 .

[11]  D. Secrest,et al.  Collisional excitation of rotation for a three-dimensional diatomic oscillator☆ , 1971 .

[12]  S. B. Atienza-Samols,et al.  With Contributions by , 1978 .

[13]  F. McCourt,et al.  Inelastic differential and integral cross sections for 2S+1.SIGMA. linear molecule-1S atom scattering: the use of Hund's case b representation , 1983 .

[14]  J. Launay,et al.  Molcol: A program for solving atomic and molecular collision problems , 2000 .

[15]  Wang,et al.  Photoassociation of Ultracold Atoms: A New Spectroscopic Technique. , 1999, Journal of molecular spectroscopy.

[16]  Patterson,et al.  Buffer-gas loading of atoms and molecules into a magnetic trap. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[17]  G. Meijer,et al.  Transverse stability in a Stark decelerator , 2006 .

[18]  P. Pillet,et al.  Formation of ultracold molecules (T≤200 μK) via photoassociation in a gas of laser-cooled atoms , 2001 .

[19]  David E. Manolopoulos,et al.  An improved log derivative method for inelastic scattering , 1986 .

[20]  R. Krems,et al.  Editorial: Quo vadis, cold molecules? , 2004 .

[21]  D. Manolopoulos,et al.  A stable linear reference potential algorithm for solution of the quantum close‐coupled equations in molecular scattering theory , 1987 .

[22]  R. Jongma,et al.  Deceleration and electrostatic trapping of OH radicals. , 2004, Physical review letters.

[23]  E. Bodo,et al.  Vibrational quenching at ultralow energies: Calculations of theLi2(Σg+1;ν⪢0)+Hesuperelastic scattering cross sections , 2006 .

[24]  R. H. Wynar,et al.  Molecules in a bose-einstein condensate , 2000, Science.

[25]  A modified Variable-Phase algorithm for multichannel scattering with long-range potentials , 2003 .

[26]  James K. G. Watson,et al.  Rotational Spectroscopy of Diatomic Molecules , 2003 .

[27]  W. Lester,et al.  Coupled channel study of rotational excitation of H2 by Li+ collisions , 1973 .

[28]  William H. Press,et al.  Numerical recipes , 1990 .

[29]  J. Marden,et al.  Erratum FGF-mediated mesoderm induction involves the Src-family kinase Laloo , 1998, Nature.

[30]  B. R. Johnson,et al.  The multichannel log-derivative method for scattering calculations , 1973 .

[31]  G. Meijer,et al.  Production and application of translationally cold molecules , 2003 .

[32]  M. Alexander.  Hybrid quantum scattering algorithms for long‐range potentials , 1984 .

[33]  T. A. Green,et al.  Variable Phase Approach to Potential Scattering , 1968 .

[34]  A. Degasperis.  Generalization of the phase method to multi-channel potential scattering , 1964 .

[35]  R. Krems.  Molecules near absolute zero and external field control of atomic and molecular dynamics , 2005, physics/0504156.

[36]  R. T. Pack.  Space‐fixed vs body‐fixed axes in atom‐diatomic molecule scattering. Sudden approximations , 1974 .