Re: extendedLagrangian for non-scalar colvar

From: Jerome Karp (
Date: Thu Dec 10 2015 - 12:05:51 CST

Perfect - thank you very much for your help.

- Jerry Karp

On Thu, Dec 10, 2015 at 12:18 PM, Jérôme Hénin <> wrote:

> Hi Jerry,
> That's correct, extendedLagrangian only works for a scalar colvar. You can
> access individual Cartesian coordinates as "distancez" colvar components,
> setting the axes to x, y, and z, respectively.
> Best,
> Jerome
> On 10 December 2015 at 17:45, Jerome Karp <
> > wrote:
>> Dear NAMD users,
>> I am trying to use the extendedLagrangian feature for a non-scalar colvar
>> (specifically, the "cartesian" colvar new to NAMD 2.11). When I do this,
>> though, I get this error message: "colvars: Trying to assign a colvar value
>> with type "scalar number" to one with type "n-dimensional vector"." Is
>> this because the extendedLagrangian only works for a scalar colvar? If so,
>> is there a way to use an extendedLagrangian for each coordinate of an atom
>> (i.e., add a fictitious particle corresponding to each of the x, y, and z
>> of a given atom)? It seems like the only way to get coordinates of an atom
>> as a colvar is using the cartesian colvar, or use the distanceVec colvar
>> with one of the groups being a dummy atom; in either case, the colvar is a
>> non-scalar, so that wouldn't work.
>> Thank you for any help you can provide.
>> Sincerely,
>> Jerry Karp

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