Desktop mechanical calculator

In 1951 an international conference was held at Shelter Island near Long Island in New York, N.Y. Most of the leading figures in quantum chemistry were present. Two persons there symbolized the phasing out of desktop mechanical calculators (Prof. Kotani from Japan) and the phasing in of electronic digital computers (Prof. Roothaan of the United Sates). That was the first major conference with a focus on the emerging computer in theoretical chemistry [1],... 

In practical terms, molecular mechanics calculations may easily be performed on molecules comprising several thousand atoms. Additionally, molecular mechanics calculations are sufficiently rapid to permit extensive conformational searching on molecules containing upwards of a hundred atoms. Modern graphical based programs for desktop computers make the methods available to all chemists. 

The quantum mechanical calculations are carried out on a Pentium desktop computer with commercial software. The HYPERCHEM input files (H1N) for the various species contain charge densities and a complete description of the geometric and energy properties of the neutral molecule and anion. These compact files are an efficient way to store and communicate this information [1],... 

Speedy and accurate desktop computers and modern programs such as HYPERCHEM place quantum mechanical calculations within the reach of any experimental chemist. The CURES-EC procedure simulates equilibrium methods of measuring electron affinities by calculating the difference between the optimized forms of the anion and neutral. The READS-TCT determination of charge densities in anion complexes simulates thermal charge transfer experiments. The effect of... 

Molecular mechanics has become a standard method in computational chemistry and is extensively used to solve problems in organic chemistry, in medicinal chemistry, and in many other areas of chemistry. Today, sophisticated computer graphics interfaces are generally used in connection with molecular mechanics calculations. The molecule to be studied may conveniently be constructed on the computer screen and the setup for the calculation may be done simply by choosing one or several computational options displayed by the graphics interface. In addition, various molecular mechanics methods are implemented on personal desktop computers or small workstations. This technological advance has drastically increased access to molecular mechanics calcu-... 

It matters little whether we can fully understand a new scientific principle, or whether we like it and feel comfortable with it. What matters most is whether we can use it to make valuable things (without doing any harm, of course). Programs that will operate in a desktop computer can now use quantum mechanics calculations to design new medicines and new microwave semiconductors for cellular phones, things which are obviously of great value. 

Chem3D can carry out molecular dynamics calculations on laptop or desktop computers. It also carries out molecular mechanics calculations. Information is available at http //www.cambridgesoft.com. 

All the structural models in this book are computer-drawn. To make sure they accurately portray bond angles, bond iengtiis, torsional interactions, and steric interactions, the most stable geometry of each molecule has been calculated on a desktop computer using a commercially available molecular mechanics program based on work by N. L. Allinger of the University of Georgia. 

A torsion pendulum interfaced with a desktop computer form an automated instrument for dynamic mechanical characterization of polymeric materials. The computer controls the initiation of the oscillations, collects the digitized data and calculates the shear modulus and loss modulus from the damped oscillations, utilizing one of four methods of analysis ... 

Advances in interpretation. Experimental KIEs are interpreted using quantum mechanical and/or bond order vibrational analysis (BOVA) approaches to yield the experimental transition state. In systems that are well understood, the accuracy of experimental TS structures derived using a BOVA unified model rivals X-ray crystallography of stable molecules. The largest advance in KIE interpretation since the description of BOVA by Sims and Lewis " has been the increase in computational power available to the average chemist. Previously, vibrational models were reduced to a minimal number of atoms to make them computationally tractable. Today, a desktop computer can perform BOVA calculations with hundreds of atoms. The accessibility of post-Hartree-Fock calculations to the average chemist has made ab initio calculations a routine part of TS analysis, and made possible the structure interpolation approach to BOVA. 

---