CamCASP/Bugs/7 - Revision history

import>Am592 at 13:48, 30 June 2011

2011-06-30T13:48:26Z

← Older revision		Revision as of 13:48, 30 June 2011
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	[[ CamCASP ]] => [[ Bugs ]] => Polarizabilities		[[ CamCASP ]] => [[ CamCASP/Bugs \| Bugs ]] => [[CamCASP/Bugs/7 \| Polarizabilities ]]

	Most of the polarizabilities generated by CamCASP show the expected monotonic decrease with increasing imaginary frequency. A few, however, depart wildly from this behaviour. In the example case of formamide, we get, for C,		Most of the polarizabilities generated by CamCASP show the expected monotonic decrease with increasing imaginary frequency. A few, however, depart wildly from this behaviour. In the example case of formamide, we get, for C,

import>Am592 at 13:45, 30 June 2011

2011-06-30T13:45:20Z

← Older revision		Revision as of 13:45, 30 June 2011
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			[[ CamCASP ]] => [[ Bugs ]] => Polarizabilities

	Most of the polarizabilities generated by CamCASP show the expected monotonic decrease with increasing imaginary frequency. A few, however, depart wildly from this behaviour. In the example case of formamide, we get, for C,		Most of the polarizabilities generated by CamCASP show the expected monotonic decrease with increasing imaginary frequency. A few, however, depart wildly from this behaviour. In the example case of formamide, we get, for C,
	20 20		20 20

import>Ajs1 at 11:19, 9 June 2009

2009-06-09T11:19:22Z

← Older revision		Revision as of 11:19, 9 June 2009
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	The fit is still pretty good: r.m.s. error 0.073% for weight 6 compared with 0.042% for weight 4. Even with weight 6 there are some anomalous cases, especially O 20 20, but the absolute values are small.		The fit is still pretty good: r.m.s. error 0.073% for weight 6 compared with 0.042% for weight 4. Even with weight 6 there are some anomalous cases, especially O 20 20, but the absolute values are small.

			Later: I realise that the off-diagonal components of the polarizability don't have to decrease monotonically -- the numerators in the sum-over-states expression may have different signs and decay at different rates. However the diagonal ones should be positive everywhere and should decay monotonically.
	Ideally we should force the monotonic decrease in magnitude, but I don't see how to do it, even if we fitted all frequencies together.

			I'm exploring the frequency behaviour of the unrefined polarizabilities. It may be possible to represent them by pseudo-DOSD expressions with just a few terms -- maybe only one -- in which case pfit could be modified to fit the parameters in those expressions rather than the individual values.

import>Ajs1 at 11:12, 9 June 2009

2009-06-09T11:12:35Z

← Older revision		Revision as of 11:12, 9 June 2009
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	11.43900000 11.41700000 7.41600000 2.64700000 +++		11.43900000 11.41700000 7.41600000 2.64700000 +++
	0.42400000 0.01400000		0.42400000 0.01400000
	with similar behaviour for C 11c 20, C 22c 22s and O 11c 20, but none of the other cases~~. Except possibly for 11c 20 the numbers are too big to be attributable to rounding error~~. Removing the "options tests" line from the data to get the standard grid makes things even worse:		with similar behaviour for C 11c 20, C 22c 22s and O 11c 20, but none of the other cases. Removing the "options tests" line from the data to get the standard grid makes things even worse:
	20 20		20 20
	-9.88200000 -9.52700000 -7.58300000 -2.61900000 +++		-9.88200000 -9.52700000 -7.58300000 -2.61900000 +++
Line 13:		Line 13:
	25.60290131 18.22199084 10.00593354 3.58000511 +++		25.60290131 18.22199084 10.00593354 3.58000511 +++
	0.63051681 0.02341723		0.63051681 0.02341723
			Weight 5 improves matters, but weight 6 is needed to get sensible results:
			20 20
			20.80100000 20.83700000 20.99700000 21.01100000 +++
			19.14900000 14.68600000 8.43300000 2.77400000 +++
			0.39500000 0.01400000
			The fit is still pretty good: r.m.s. error 0.073% for weight 6 compared with 0.042% for weight 4. Even with weight 6 there are some anomalous cases, especially O 20 20, but the absolute values are small.

			Ideally we should force the monotonic decrease in magnitude, but I don't see how to do it, even if we fitted all frequencies together.

import>Ajs1 at 10:36, 3 June 2009

2009-06-03T10:36:18Z

@@ Line 4: / Line 4: @@
 .43900000     11.41700000      7.41600000      2.64700000 +++
 .42400000      0.01400000
-with similar behaviour for C 11c 20, C 22c 22s and O 11c 20, but none of the other cases. Except possibly for 11c 20 the numbers are too big to be attributable to rounding error.
+with similar behaviour for C 11c 20, C 22c 22s and O 11c 20, but none of the other cases. Except possibly for 11c 20 the numbers are too big to be attributable to rounding error. Removing the "options tests" line from the data to get the standard grid makes things even worse:

import>Ajs1 at 14:13, 2 June 2009

2009-06-02T14:13:08Z

New page

Most of the polarizabilities generated by CamCASP show the expected monotonic decrease with increasing imaginary frequency. A few, however, depart wildly from this behaviour. In the example case of formamide, we get, for C,
20 20
3.74300000 3.98200000 5.26700000 8.33300000 +++
11.43900000 11.41700000 7.41600000 2.64700000 +++
0.42400000 0.01400000
with similar behaviour for C 11c 20, C 22c 22s and O 11c 20, but none of the other cases. Except possibly for 11c 20 the numbers are too big to be attributable to rounding error.