Cambridge Analytical Derivatives Package

R. D. Amos and J. E. Rice, CADPAC The Cambridge Analytic Derivatives Package, issue 4.1, Cambridge, 1990. 

Amos, R. D. (1984a). CADPAC The Cambridge Analytic Derivative Package, Publ. 

Cambridge Analytical Derivatives Package. Ab initio calculations. Cray and other versions. 

Tel. 44-223-336384, e-mail cadpac theory.chemistry.cambridge.ac.uk Cambridge Analytical Derivatives Package. General purpose ab initio calculations. Cray and other versions. Spectro for analyzing anharmonic force fields and calculating positions and intensities of lines, including Fermi resonance effects. 

R. D. Amos with contributions from I. L. Alberts, J. S. Andrews, S. M. Colwell, N. C. Handy, D. Jayatilaka, P. J. Knowles, R. Kobayashi, K. E. Laidig, G. Laming, A. M. Lee, P. E. Maslen, C. W. Murray, J. E. Rice, E. D. Simandiras, A. J. Stone, M.-D. Su and D. J. Tozer, The Cambridge Analytic Derivatives Package-A suite of quantum chemistry programs, Issue 6, Cambridge, 1995. Further details can be found at the website http //www-theor.ch.cam.ac.uk/software/cadpac.html... 

R.D. Amos, et ai, CADPAC, The Cambridge Analytic Derivatives Package, Cambridge, UK, 1995. 

RD Amos, IL Alberts, JS Andrews, SM Colwell, NC Handy, D Jayatilaka, PJ Knowles, R Kobayashi, GJ Laming, AM Lee, PE Maslen, CW Murray, P Pahnieri, JE Rice, ED Simandiras, AJ Stone, MD Su, DJ Tozer. CADPAC The Cambridge Analytical Derivatives Package. Cambridge, UK. 

The Cambridge Analytic Derivatives Package Issue 6, Cambridge, 1995. A suite of quantum chemistry programs developed by R.D. Amos with contributions from I.L. Alberts, J.S. Andrews, S.M. Colwell,... 

CADPAC (Cambridge analytical derivatives package, ket.ch.cam.ac.uk/) is an ab initio program that contains Hartree-Fbck, density-functional, and commonly used correlation methods. 

Amos RD, Alberts IL, Andrews JS, ColweU SM, Handy NC, Jayatilaka D, Knowles PJ, Kobayashi R, Laidig KE, Laming G, Lee AM, Maslen PE, Murray CW, Rice JE (1995) In Simandiras ED, Stone AJ, Su M-D, Tozer DJ (ed) CADPAC the Cambridge analytic derivatives, package issue 6. Cambridge... 

Amos RD, Rice JE (1987) CADPAC The Cambridge Analytical Derivatives Package, issue 4.0, Cambridge... 

If we have to use non-orthogonal wavefunctions, then the natural one-electron orbitals in which to express them are the SCF molecular orbitals of the non-interacting molecules. From these we can construct antisymmetrized (determinantal) wavefunctions in which some orbitals of each molecule are occupied. Because of the non-orthogonality of the orbitals, these determinant al wavefunctions will also be non-orthogonal. It is possible to construct a perturbation theory in which the wavefunction is expanded in terms of these determinants. Fortunately it is possible to formulate it in such a way that the separation of the Hamiltonian into an unperturbed part and a perturbation is unnecessary. The resulting Intermolecular Perturbation Theory (IMPT) has been incorporated into the Cambridge Analytical Derivatives Package (CADPAC)i ... 

Cambridge Analytical Derivatives Package ab initio calculations. 

These MP2 codes form a central feature of the Cambridge Analytic Derivatives Package[8] (CADPAC). On a CRAY-XMP, it is often found that the MP2 second derivative algorithm mns at 80 Mflops, and with our disc limitation of 4 Gbytes, in effect we are limited to calculations with less than 200 basis functions. However, this enables substantial calculations to be performed on small molecules, as we shall demonstrate. 

Further technical details are that the SCF fourth derivatives were determined by central differences of the analytic SCF third derivatives, using cartesian displacements of 0.001 ao- These calculations, all carried out at the SCF optimised geometry, were performed with the codes developed by J.F. Qaw[10]. The determination of the spectroscopic constants was possible with the program SPECTRO[20], specially designed to derive this informatton from a quartic force field. The MP2 analytic derivative calculations were performed with the Cambridge Analytic Derivatives Package (CADPAC), this edition being provided by R.D. Amos and J.E. Rioe[8]. 

Amos RD, Rice JE (1988) Program CADPAC The Cambridge Analytic Derivatives Package, University of Cambridge, Cambridge, England ... 

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