12 resultados para He

em Brock University, Canada


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Thick gold single crystals of high quality were prepared for Rutherford Backscattering Dechanneling studies by electropolishing and annealing. The variation.; with temperature of the Random Fraction versus Depth spectrtnn for 2 MeV He+ on < 110> gold was extracted from measured Aligned and Random (Energy) Spectra. The measured dechanneling rate showed a sixfold increase in going from 4loK to 293°K and is in reasonable agreement with calculations made using the Steady Increase in Transverse Energy (SITE) approximation.

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Exch~nge energy of the He-He system is calculated using the one-density matrix which has been modified according to the supermolecular density formula quoted by Kolos. The exchange energy integrals are computed analytically and by the Monte Carlo method. The results obtained from both ways compared favourably,with the results obtained from the SCF program HONDO

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The one-electron reduced local energy function, t ~ , is introduced and has the property < tL)=(~>. It is suggested that the accuracy of SL reflects the local accuracy of an approximate wavefunction. We establish that <~~>~ <~2,> and present a bound formula, E~ , which is such that where Ew is Weinstein's lower bound formula to the ground state. The nature of the bound is not guaranteed but for sufficiently accurate wavefunctions it will yield a lower bound. ,-+ 1'S I I Applications to X LW Hz. and ne are presented.

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The infinitesimal differential quantum Monte Carlo (QMC) technique is used to estimate electrostatic polarizabilities of the H and He atoms up to the sixth order in the electric field perturbation. All 542 different QMC estimators of the nonzero atomic polarizabilities are derived and used in order to decrease the statistical error and to obtain the maximum efficiency of the simulations. We are confident that the estimates are "exact" (free of systematic error): the two atoms are nodeless systems, hence no fixed-node error is introduced. Furthermore, we develope and use techniques which eliminate systematic error inherent when extrapolating our results to zero time-step and large stack-size. The QMC results are consistent with published accurate values obtained using perturbation methods. The precision is found to be related to the number of perturbations, varying from 2 to 4 significant digits.

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Letter (1 typed page) to Louis J. Cahill from the Managing Editor [no indication of who he works for – same signature as is on the Knox, Harvie and Foss letter] saying that he has found various references to Samuel Zimmerman being active in the erection of the first suspension bridge and its Roebling successor, July 20, 1948.

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Letter (2 pages, handwritten) to S.D. Woodruff asking if he could handle a loan which has been requested. The letter is signed Jarvis, Conklin and Co., March 31, 1883.

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Printed blank by which John Brown Cullen solemnly declares that he is experienced in the art of measuring and culling timber. He states that he is entering into the service of Burton and Bro. of Barrie He will make out the specification of the timber in berths 192 and 198 and submit his findings to Burton and Brother, Oct. 22, 1877.

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Letter with the salutation “Dear Sir” It is signed by John I. Mackenzie in which he states that he got the Globe to publish a letter about the Long Point expats which had been sent to the Ottawa Times. Most of the handwriting is illegible, Oct. 26, 1870.

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Letter to S.D. Woodruff from John I. Mackenzie saying that he is closing up the commissariat accounts at Long Point. There is still an amount outstanding and he asks Mr. Woodruff to send a cheque. He hopes that Mr. Woodruff had a good time at Long Point (2 pages, handwritten), Nov. 23, 1881.

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Letter to Louis Cabot from S.D. Woodruff stating that he will sell his Point McMillen [McMillan], Michigan shares, but he doesn’t think that the sheriff will sell his Long Point shares, Jan. 6, 1886.

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Letter (1 ½ pages, handwritten) to S.D. Woodruff from Louis Cabot saying that he owes Mr. Woodruff an apology. He thought he had done 20, but he thinks it would be wise to take 9 of the sheriff’s shares. This letter is accompanied by an envelope, Feb. 8, 1886.

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Letter to S.D. Woodruff from an illegible signature stating that he suspects a clerical error in one of the columns, n.d.