Page 56 out of 84 total pages , Page 12 out of 16 pages in this chapter
This section describes how an ASCII file may be constructed that is self readable by a quadrupolar interaction. The file can be created with any editor and is read with the quadrupolar interaction member function "read". It is important to keep in mind the structure of our interaction as given in Section 4.17.2 on page 233. We will need the set of {
, dzz, h, q, f} specified for each quadrupolar interaction we wish to create. Of course, there are several other ways of declaring a quadrupolar tensor than with the use of these five values. To accomodate different tensor nomenclature (i.e. spherical versus Cartesian, oriented versus PAS, etc.), GAMMA quadrupolar interactions will recognize different sets of parameters! Thus, the following sections detail "parameter sets" which can be used for this purpose.
Perhaps the simplest way to designate a quadrupolar interaction is to provide the quadrupolar coupling constant, an asymmetry parameter, and a tensor orientation relative to the principal axis system. This would be the set of parameters {I, QCC, h, q, f}.
| Parameter | Units | Examples Parameter (Type) : Value - Statement |
|---|---|---|
| QI | none | |
| QCC | KHz | |
| Qeta | none | |
| Qtheta | degrees | |
| Qphi | degrees |
By including these parameter statements (right column) in an ASCII file a GAMMA quadrupolar interaction can be set with the read function. For example, the code below reads "file.asc".
Three things to remember; 1.) These ASCII files are read as GAMMA parameter set files so that they may contain additional likes of information and additional parameters. Things such as column spacing is not important - read about GAMMA parameters sets for full details. 2.) All parameters can have a (#) appended to the name and parameters with that number will be selected if the number is given as an argument in the read function. 3.) There are name variations allowed even within these five parameters. For example, users may specify a quadrupolar frequency rather than a quadrupolar coupling constant. The spin quantum number can be read from an isotope declaration rather than with use of parameter QI. Another variation would be to put an interaction "index" on these parameters when multiple interactions must be designated within the same ASCII file. Here are the possibilities.
Quadrupolar Spin Quantum Number: QI, Iso
The quadrupolar spin quantum number must be specified. This can be accomplished with parameters using either of the two names below or these names with a (#) added as a suffix. The value of QI must be a positive multiple of 1/2 and greater than 1/2. The value of Iso must designate a spin isotope having a spin quantum number greater than 1/2. If both QI and Iso are set in the same file, the QI value will be used to set up the quadrupolar interaction..
| Parameter | Assumed Units | Examples Parameter (Type=1,3) : Value - Statement |
|---|---|---|
| QI | none | |
| Iso | none |
1
Shown are two possible parameters used to set the quadrupolar spin quantum number. Parameter type 1 indicates a double precision number parameter. Parameter type 2 indicates a string parameter. |
Quadrupolar Frequency: WQ, WQkHz, WQKHz, WQHz, WQMHz
The quadrupolar frequency can be specified. This can be accomplished with parameters using any of the names below or these names with a (#) added as a suffix. The default units for WQ are KHz other names can be used to set the value in particular units. Note that this parameter is related to the quadrupolar coupling constant which is specified with "(N)QCC" parameters. If both QCC and WQ are set in the same file, the quadrupolar frequency will be used to set up the quadrupolar interaction.
| Parameter | Assumed Units | Examples Parameter (Type=1) : Value - Statement |
|---|---|---|
| WQ | KHz | |
| WQMHz | MHz | |
| WQHz | Hz |
Quadrupolar Coupling Constant: QCC, QCCkHz, QCCKHz, QCCHz, QCCMHz
The quadrupolar coupling constant can be specified. This can be accomplished with parameters using any of the names above, these same names with an "N" as a prefix, and/or these names with a (#) added as a suffix. The default units for QCC are KHz other names can be used to set the value in particular units. Note that this parameter is related to the quadrupolar frequency which is specified with "WQ" parameters. If both QCC and WQ are set in the same file, the quadrupolar frequency will be used to set up the quadrupolar interaction.
| Parameter | Assumed Units | Examples Parameter (Type=1) : Value - Statement |
|---|---|---|
| QCC | KHz | |
| NQCCMHz | MHz | |
| QCCHz | Hz |
Quadrupolar Asymmetry
The asymmetry parameter must be within the range of [0, 1]. This parameter does not need to be set for a quadrupolar interaction definition, it will be assumed 0 if unspecified.
| Parameter | Assumed Units | Examples Parameter (Type=1) : Value - Statement |
|---|---|---|
| Qeta | none |
1
Parameter type 1 indicates an integer parameter. |
Quadrupolar Theta Orientation
The angle theta which relates the quadrupolar interactions orientation down from the z-axis of its PAS may be set. This is not essential and will be taken as zero in left unspecified.
| Parameter | Assumed Units | Examples Parameter (Type=1) : Value - Statement |
|---|---|---|
| Qtheta | degrees |
1
Parameter type 1 indicates an integer parameter. |
Quadrupolar Phi Orientation
The angle phi which relates the quadrupolar interactions orientation over from the x-axis of its PAS may be set. This is not essential and will be taken as zero in left unspecified.
| Parameter | Assumed Units | Examples Parameter (Type=1) : Value - Statement |
|---|---|---|
| Qphi | degrees |
1
Parameter type 1 indicates an integer parameter. |
Perhaps the simplest way to designate a quadrupolar interaction is to provide the quadrupolar coupling constant, an asymmetry parameter, and a tensor orientation relative to the principal axis system. This would be the set of parameters {I, QCC, h, q, f}.
| Parameter | Units | Examples Parameter (Type) : Value - Statement |
|---|---|---|
| QI | none | |
| QCC | KHz | |
| Qeta | none | |
| Qtheta | degrees | |
| Qphi | degrees |
By including these parameter statements (right column) in an ASCII file a GAMMA quadrupolar interaction can be set with the read function. For example, the code below reads "file.asc".
|
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© 1996 Scott A. Smith, The NHMFL, and The Florida State University. All Rights Reserved. |