In VMD Main window select the molecule that you want to save, then in the menu "FILE" you press "Save Coordinates", in the pop-up window that will appear, you select the elements that you want to save (in case you have several selections in the representation), the output format and number of frames that you want to save (if you only want 1, first and last must be equal).

Best wishes

Hi,

Thank you for the reply.

There is First Last and Stride under Frames.

What is Stride? What number should be given when first and last frame are the same?

First and Last correspond to the first and last frames respectively that were read from the molecular dynamics in question (example: if you read the trajectory file, by default, First = 0 and Last = -1, this values are index). You can only take one set of frames by changing these values ​​when opening the trajectory file.

Stride corresponds to the interval value at which frames are read.

For example: suppose that you has a trajectory containing 10 frames, first = 0, last = -1 (equivalent to frame 10 with index=9) and stride = 1, this means that you will visualize a total of 10 structures, if stride = 2, it means that it will only read the frames 0,2,4,6,8, so that it will only visualize 5 structures and so respectively.

If First and Last a priori are equal it means that it only has one structure in that trajectory file, so that it can only save that structure, therefore no frame can be selected (since it only has one).

Best wishes

Hello Mario S. Valdés-Tresanco! I have a question. If i want only to save de last frame and the total of the trajectory in 101. What should I select in first and last frames? Thank you very much

Elizabeth Quintero It would be similar. If you only want to save only one frame, First and Last must be the same number, in your case it would be 101.

Best wishes.

Thank you for your quick response Mario S. Valdés-Tresanco . The program show me: No timesteps selected; trajectory file will not be written. I save the trajectory all at one so, I don't understand the mistake. I would appreciate if you can advise me.

@Elizabeth Oh sorry, my mistake, sorry about that. Actually it must be 100 because these are indices (starting from 0 and ending at n-1). I notice that in the last version of the VMD -1 does not appear anymore but the index of the last frame (n-1). In principle it should work with 100 in your case.

Let me know any problem.